The political theorist Hannah Arendt famously coined an immortal phrase to describe captured Nazi fugitive Adolf Eichmann: the banality of evil. Set in a creepy, clammy, morally degraded England where unspeakable pagan horrors take place in humdrum suburbs and shabby caravan parks, director Ben Wheatley's savagely funny comedy thrillers capture something similar but different: the evil of banality.

Wheatley's 2009 debut feature, Down Terrace, was shot in just two weeks in the run-down residential edgelands around his adopted hometown of Brighton. Centred on the domestic bickering of a suburban crime family led by domineering ex-hippie patriarch Bill (Robert Hill), the film contains very little violence, partly due to budget limitations, but it still crackles with malevolent power and delivers a high body count. Wheatley modeled the central couple partly on Tony and Cherie Blair, though they behave more like Fred and Rose West. Think GoodFellas meets Gavin & Stacey.

Next came Kill List (2011), a nerve-shredding psycho-thriller about a pair of Iraq war veterans turned freelance hit men. Forced to take on grisly execution jobs by economic and domestic pressures, the mentally fragile anti-hero Jay (Neil Maskell) uncovers a hellish hidden England of diabolical nudist cults and ritual sacrifice. The disturbing final scenes are lifted directly from Wheatley's own childhood nightmares. And yet, as with Down Terrace, it is Jay's suburban family rows that generate the most teeth-grinding tension. Recognisable reality is always more scary than melodramatic fantasy. Think The Wicker Man directed by Sam Peckinpah.

So much for cult kudos. Now Wheatley is poised for his breakthrough success with Sightseers, an inspired comedy-horror road movie written by its two stars, comedians Alice Lowe and Steve Oram. A caravan holiday through the mundane tourist hot spots of the Midlands and northern England turns into a bloodbath when mild-mannered Tina (Lowe) discovers her new boyfriend, ginger-bearded rambler Chris (Oram), is a serial killer. It is Wheatley's most overtly comic feature to date, although his screenwriter wife Amy Jump added plenty of dark material to the original script. Never has provincial Middle English crapness seemed so psychotically sinister. Think Nuts In May crossed with Natural Born Killers.

Wheatley began his career directing and writing TV comedy with a surreal, macabre edge – cult shows like Modern Toss, Time Trumpet and Ideal. Gifted comic actors such as Michael Smiley, a veteran of Simon Pegg's much-loved Spaced, are regulars in his screen repertory company. Edgar Wright, director of Spaced and Shaun Of The Dead, co-produced Sightseers.

And yet Wheatley's washed-out, naturalistic, artfully drab aesthetic comes from a far more serious tradition: the heavyweight British social dramas of the 1970s and 1980s. He cites Alan Clarke, legendary director of classic state-of-the-nation polemics like Made In Britain and Rita, Sue and Bob Too, as a key influence. It is no coincidence that the unhinged protagonists in Kill List and Sightseers are reeling from recession and redundancy. These are blood-splattered genre mash-ups with a Play For Today-style political subtext. Social-realist slasher movies. Kitchen sink noir.

Music is another vital mood-shaper in Wheatley's audio-visual horrorscapes. His regular composer James Williams is a seasoned session guitarist who has played with Paul Weller, Terry Hall, This Mortal Coil and many more. Kill List was originally cut to a slowed-down selection of slithering, unsettling ambient pieces by the veteran avant-garde composer Morton Feldman, before Williams composed his own score in the same bone-chilling mode. He and Wheatley then added sampled sounds of pigs, sharks and even a guillotine to the film's musique concrète mix. The soundtrack to Sightseers, meanwhile, sets up a dialogue between 1980s synth-pop and 1970s Krautrock, as Soft Cell and Frankie Goes To Hollywood rub shoulders with Harmonia and Popol Vuh.

Wheatley's next movie will be A Field In England, a psychedelic period horror yarn set during the Civil War, cheaply shot on black-and-white in just eight days. After that he will direct his first medium-budget US production, the monster-blasting sci-fi Freakshift. Maybe he will then take the Peter Jackson route and abandon lo-fi social-realist horror altogether for effects-driven blockbusters. But for now, his impressive body of work remains firmly shackled to the indie kitchen sink. And Sightseers is the funniest, darkest, most painfully British film in decades.

How deliberate are the uncanny parallels between Sightseers and Mike Leigh's classic 1976 TV drama Nuts In May?

Ben Wheatley: I hadn't seen it, weirdly enough. I've seen a lot of Leigh stuff but I hadn't seen Nuts In May. So I watched it later and, er, OK! It's quite similar! There are elements in it. Steve Oram says there's not that many camping movies so they all look the same, so Carry On Camping is actually quite a heavy influence too... but anyway I went back and had a look, took some stuff out. There's no getting away from the fact that Steve looks like the main bloke, but that's a quirk of genetics on Steve's part.

Sightseers is the first of your films that you did not conceive or co-write yourself. Does that make it less personal than Down Terrace or Kill List?

BW: I think it's a shared experience. We were all kids, we all went to these kind of places. For me it was more Blackgang Chine and the Isle of Wight, but I think Bluebell Railway isn't amazingly different from Crich. So I think we all understand that. I understood the characters when I read it, and I kind of supported them. I don't necessarily condone the murder of innocent random people... ha! But I can see their frustration.

You have vintage Krautrock and synth-pop on the Sightseers soundtrack. How important is the music in your films?

BW: All the films have an idea about the music, there's a scheme for it. In Sightseers there were two themes going on, one was about cover versions because she was taking him over and becoming exactly what he loved, doing her version of it. So you get 'Season Of The Witch' and 'Tainted Love' as the two counterpoints. And the other idea was, I'd been getting into Krautrock quite a lot, and I realised I'd been sold this bill of goods when I was a kid that the new wave of punk had been something we invented in the UK, but actually if you look at history you realise it was made in Germany. Obviously music's fluid and I'm sure you can trace Krautrock from other places as well - Neu! being for me the centre of a lot of music, obviously Harmonia came out of Neu! So I had this idea that there would be two sets of music – this big, brassy synth music that happened in the '80s in the UK, but underneath it was the German music where that had really come from. So it was like the characters had different levels of reality about them.

That's a great concept, but you may need to hand out instruction manuals to filmgoers...

BW: Yes, it's a bit of leap, ha! But also the German stuff is really good. So it made sense to me, and if it doesn't to other people I don't care. It's the music I really like.

No pig or shark noises on the soundtrack this time?

BW: I don't think so. There's a lot of sound design but no pigs this time.

All your films so far have balanced dark humour with savage violence, to varying degrees. Are comedy and horror two sides of the same genre?

BW: Kind of. They're both types of cinema that you can see in the room whether it's worked or not. You see horror from jumps and screams, and obviously you see comedy from laughs. There are gags in both of them, set-ups and pay-offs and timing. There are physical things, and jokes returning. But I think comedy and horror are mainly similar because basically comedy is about misfortune, most of the time, or one big strand of it anyway. You've got slapstick, which is basically really violent. There is also whimsical comedy, which doesn't have anything to do with suffering, but most comedy is about someone else's misfortune. So I think they are joined at the hip in that way.

Often the most powerful comedy is just a shade away from violence...

BW: Yeah – or actually having violence. I was re-watching The Young Ones the other day and I had forgotten how subversive and crazy that show was, compared to now. It couldn't happen now because it would probably cost about a million quid an episode. That's all about violence. The Three Stooges too, and out of The Three Stooges you get The Evil Dead – so it's all interconnected.

Your films all seem to suggest that suburban family life can be much more disturbing than even extreme violence. Is that something you believe?

BW: Those ideas are definitely in there. The family stuff is more horrific just because we understand it, we've experienced it. I've never murdered anyone, or even really been in a fight, so that kind of stuff doesn't really affect people generally when they watch films. But they do know what being in a family is like – it can be claustrophobic and difficult, everyone vying for attention or for control. Definitely in Kill List, that bit when they shot a priest in the head, no one was bothered by that at all. Ha! But people were more upset by the screaming row with the kid there, because you're in the child's point of view, but if you've got kids you understand how the parents feel as well, so you get double feedback off that. I've got a nine-year-old and the thing I felt when he started growing up was I could see things through his eyes but I could also see through my parents' eyes at the same time. And that feedback was really scary: you start to understand what happened to you when you were little, and what your parents were thinking, and you realise how young your own parents were. That's why those things seem harsher in the films than other elements, because the murder stuff is more genre and plot.

Taken as a whole, your films depict modern Britain as a creepy, sinister, almost demonic place. Is that deliberate?

BW: I guess. I am a glass half empty person, ha! I do feel like that bit, but I think the theme that runs through it more is that idea that civilisation is wafer-thin, and that underneath we are quite savage islanders. There's a lot in those three films about the past and the present existing in the same point, and we are only a few steps away from committing something quite bad. It's the whole idea of what evil is – evil is such an unwieldy concept, in that the reality is it's just us. Given the right circumstances, or the wrong circumstances, you are ready to do terrible things quite quickly. I really felt it a couple of years ago, when the banks were about to fail, what would happen the next morning when you tried to get money out? Because they came really close to failing, and I thought – what food have I got in my house? What's next, you know? What happens on Day Three? It wouldn't take long...

For what? For society to collapse into a lawless zombie apocalypse like in 28 Days Later?

BW: Exactly! So I ended up buying some catapults. Ha! Luckily I didn't need to use them. But that kind of stuff is certainly in the films.

There is usually an undercurrent of political and social critique in your films. Is it true the gangster couple in Down Terrace were inspired by Tony and Cherie Blair?

BW: Yeah, it's kind of about that. They say it out loud in the film. I always found it incredible with Blair, it all hinged on him saying he believed he was right at the time, so that's OK. I didn't realise that was a defence in law, you could murder someone and say, "I thought he was a demon!" or something, and you can get away with it. So in Down Terrace, they are running a private war. That was the deep-down meaning for me anyway.

And obviously Kill List is an even more explicit comment on the morality of the Iraq war?

BW: Yeah, that is more about if you're going to use soldiers, you need to make sure the war they are going to is legal and right. These guys will lay down their lives, they will do terrible things, they will kill people for you – but you're going to damage them if they are not doing it right. My generation was brought up on Second World War movies, and the Second World War is a shining beacon of rightness because the Nazis were proper black hats and we were proper white hats – even though, if you talk to veterans, it was all a horrible fucking mess. So that was what Kill List was about. They sign up thinking they are doing right, then find out that the morality of it is all a bit more up for grabs, so they end up shifting their position by becoming mercenaries, then becoming hitmen, because that's the same as being a soldier... isn't it?

Give us a few words on your next films, A Field In England and Freakshift...

BW: A Field in England is black-and-white, art film, period piece, in Old English, lots of drug taking. It's my calling card for Hollywood, yeah, ha! And then Freakshift is $20 million of monsters, shotguns, American-set, Hill Street Blues meets Doom. A Field in England is shot, and Freakshift hopefully we will be shooting in April.

Has all the positive buzz around Sightseers boosted your profile with the big US studios yet?

BW: Not yet. It might do when it gets an American release. But that just means they will stop sending me scripts about murdered children and start sending me comedy scripts. Which would be nice.

Or maybe some comedy scripts about murdered children?

BW: Yes. That's the crossover.

Sightseers opens on November 30 in the UK.