Julian Barratt: 'Pain – that's what life is all about, isn't it?'

Julian Barratt is looking Russian. He has grown a convincing beard in readiness for playing the mayor in Gogol's classic 1836 comedy The Government Inspector. He is best known as Howard Moon – playing opposite Noel Fielding's Vince Noir in the BBC's zany comic series The Mighty Boosh – and might have found one of Moon's Hawaiian shirts more comfortable today than what he has chosen to wear: a brown tweed suit and hobnail boots. But at least he sports sunglasses. It is Riviera hot out here on the Young Vic's terrace and we are eyeing a roof eccentrically carpeted in heather.

But, first, to Gogol. How are we pronouncing him? "Goggle" and "Google" are swiftly dismissed. Next: did Barratt know Gogol urged actors to draw on the humanity of his characters instead of sending them up? How seriously is Barratt taking his part? "Very seriously," he says, morosely, adding that, if people are to laugh, "he must not be made too sympathetic". Mind you, the mayor has "engaging" points but is weak, corrupt and afraid of the government inspector. Can Barratt, as an actor, relate to that fear? "I am terrified," he admits. The critics are his government inspectors. He worries about their "knives". And he reminds me of a fact: "I have not done theatre before."

I remind him of the episode in The Mighty Boosh ("The Chokes") in which he suffers acute stage fright. He freezes before producing a hilarious bout of primal screaming. Has Barratt ever dried for real? No surprise – he has. It was during his first standup sketch at Reading University: "I ran through the back door mid-act and through fields to a lake. I was in two minds about falling in."

Perhaps you need to be masochistic to act at all? "Pain – that is what life is about, isn't it? Suffering with moments of reprieve." During our half hour in the sun, he tells me how "needy" comedians are, relying on a laugh "every 35 seconds". He worries about the silences in straight theatre. "How do you tell if it is going well?" He dreads fake laughter and demonstrates: "Hah! Hah!" – which makes me laugh. Then he looks sombre again.

His sombreness – what is it about? "Comedians are not well people," he says. "Well people are not drawn to creating." Barratt's creativity is dominated by music – he plays jazz guitar and composed all the music for The Mighty Boosh. He mentions the band of his youth: "Satan's Hoof." Was the name supposed to be funny? "No," he says. Would he describe himself as depressive? "Yes." He repeats the word thoughtfully, chewing on his prawn salad. He is serious. We both laugh. Now 43 and the father of three-year-old twin sons with comedian Julia Davis, he remarks that in middle age "all mechanisms start failing… Drink… that is not working…". He breaks off, glancing wanly at the Young Vic's fire escape.