'Obviously, if I acted like I did onstage, just walking down the street, that would be bad news. I wouldn't last fucking two minutes,' explains Jason Williamson as he's out walking his dog. The frontman of Sleaford Mods is not long back from the gym, and he's heading home soon to get on with the housework. Chatty, funny, gentle, even – off-duty Williamson is positively cuddly compared to the bile-spitting, head-slapping, geezer-nutter persona with the vein spasming in his neck at gigs.

'I like performing, deffo. Of course we put across a certain image when we play live. That tradition has been there since day one. I've got a lot of anger, yeah, sometimes I wish I wasn't like that. I try to be more diplomatic these days.'

Diplomacy is not what's got Sleaford Mods where they are today. Iggy Pop didn't call them 'undoubtedly, absolutely, definitely the world's greatest rock'n'roll band' because they pull their punches. Their cynical, politicised and arsey style has struck a chord with disillusioned audiences in Broken Britain and beyond, fed up of boybands singing anodyne love songs, and ready to hear a middle-ager from the East Midlands ranting about things that really get on his tits.

Sleaford Mods' most recent album, English Tapas – with on point, embittered and biting words by Williamson and earworm music by his head-nodding, beer-drinking, onstage hypeman and friend, Andrew Fearn – homes in on more sides of British culture that disgust him. In the past it's been 'EDL twats', dole offices, 'able-bodied vultures' declaring war on society's poorest and most vulnerable, and those who criticise Jeremy Corbyn, who Williamson describes as someone who 'reeks of compassion'. The 2017 update sounds off about The NME's website, the BHS pension nightmare and the UK's 'work like fuck' culture.

'That sadness and anger is never going away,' says Williamson. 'It's gotta be constantly in your music all the time. Because you're exposed to it in the street every day. Everything's getting worse. The same people are still just as disgusting. That anger speaks to people.'

Frequently criticised for his love of swearing, Williamson has always defended his lyrics as being how people really speak; it's the sound of people on comedowns, on the factory floor, kicking off outside pubs at closing time.

'So many artists now are talking dogshit. I don't feel they're being honest – it's an insult. Who gives a fuck about the night out you had in a club? My five-year-old and two-year-old would like that kind of music. They're too young to understand the realities of the world. Those bands may as well be calling out the numbers at the bingo on a Wednesday.'

Although Williamson's got in trouble in the past for naming and shaming the bands he thinks are guilty of blanding up the charts, he's holding his tongue today.

'There are like five or six bands at the moment that really fucking annoy me, but I'm not going to mention who they are. You live and learn. Twitter's a right playground for that kind of thing. It's pantomime, pure theatre. There will always be shit bands – I need them so I can feed off them. I'd be out a job otherwise.'

Williamson's admitted in the past that his early music had misogynistic sides to it and violent language about women. The partially reformed, toned down and grown up Williamson thinks better of that kind of toxic masculinity now, saying it reflected how angry he was at the time, and he's gradually getting better at controlling that rage now. And if their gigs sound like they'd attract a sausagefest of aggro blokes looking for a terrace-style singalong ruck, he doesn't think that's accurate either.

'A lot of music now says it's not misogynistic, even when it is. Or it's laden with pretentiousness. We've noticed much more of a female presence at gigs recently, and younger people. It's not like we get an Oasis crowd – we never had a yobbo crowd. It was more like middle-aged blokes listening to the words.'

A teetotaller since last year, Williamson has traded in his eight pints a night and coke habit to focus more on the band.

'After a while you need to stop. I got in trouble, I would stay up for three days, not go to bed. I've got two kids and a wife now, I want to keep them.'

He mentions John Doran, founder of The Quietus', memoir of drug and drink addiction, Jolly Lad, which he's been meaning to read. Like Doran, he doesn't want to preach about his wholesome new lifestyle.

'Of course giving it all up leaves an empty void. I spent so many years out my tree. I go running now, and go to the gym. I still get a bit of a crash after a tour, but that's getting better. I put all my excess energy into the band now.'

They're heading out on a UK tour next week, and English Tapas has been nominated for album of the year at this year's Q Awards, announced at the Roundhouse on Oct 18.

'We'd love to win, yeah. Andrew's not so keen on award ceremonies, all the glitz and glam. I reckon it's good for publicity though, and pushing records. The idea is to stay in the game, to survive.'

The former chicken factory and call centre worker has come a long way. But the old Williamson – the one recently described by Ted Kessler of Q as like 'Richard the Third being attacked by wasps as he attempts to enter a rave' – thankfully hasn't mellowed completely. Just after our conversation ends, he's on Twitter.

'How do you cancel shuffle play on Spotify? Fuck shuffle play. It's for cunts.'

Sleaford Mods are on tour throughout Oct & Nov; English Tapas is out now.