Ed Byrne says he's a miserable old git. He didn't celebrate his 40th birthday last year and his new show, Roaring Forties, is partly about the many things in life that annoy him. But in the flesh he's smart and funny, and as for being a party pooper... Well, not really – he's planning a celebration in November when his tour reaches Glasgow, the city where his career began 20 years ago after he had studied horticulture at the University of Strathclyde.

The Irish observational comic, who grew up in Swords in Dublin, started re-evaluating his life after that landmark birthday, as you do, and it gave him the idea for Roaring Forties, which is his trademark mix of one-liners and extended anecdotes, and covers a range of subjects from fatherhood and friendships to vasectomies and driving awareness courses . “It's about getting older,” Byrne says, “about being at an age where you're not really that old but no one thinks you're trendy anymore.”

Byrne has embraced middle age and reached the conclusion that on the whole people annoy him. “It's like a spring-clean of my life,” says Byrne, “and I've come up with reasons why you can't be my friend. There are seven billion people on the planet and I only have the time to be friends with 10 of them and so I have to choose carefully.”

What are his rules? “It's the little things that annoy me,” he says. Such as? “People who don't indicate on roundabouts, people who uses the phrase, 'Touched a nerve there', or 'I'm just making conversation'...” The list runs on.

How flexible is he? Could we negotiate if I forget to indicate just the once, for instance? “I don't have time for you! If we have to get into a debate about it, then no,” he says, laughing.

Being the married father of two young sons (with his publicist wife, Claire) has given him lots of new things to talk about on stage, but do Claire and his family, who often appear in his material, ever object? “It's something that most comics experience,” Byrne replies. “People know what you do for a living and then they complain when you mention them in the act, and I've certainly had at least one girlfriend in the past who objected.

“But my wife and my family are really funny and Claire understands what goes with the job. Actually she comes off very well and people say our relationship – very sparky, very joshing - comes across. I can't think of a time when she's said you can't use this, but if she did, I'd not use it.

“As for the kids, any stuff I do about them I seriously doubt in years to come they'll hate me for and make me pay for their therapy,” he says with a laugh. “Although I am aware that there's an age at which you have to be sensitive to their wishes and not embarrass them, but that's some years off.”

Talking of sensitive matters, Byrne finds the funny about having a vasectomy, but he was also under the surgeon's knife recently when he tried to move a compost bin in his garden and gave himself a hernia. Fans may have seen him exposing his midriff on Graham Norton's BBC programme to show off his war wounds, but they're healed now. “It's all fine, and I'm stronger than ever before,” he says. The Irishman is actually super-fit; a keen hillwalker, he recently climbed Mont Blanc and bags Munros in Scotland.

As he is about to mark 20 years in the business, has he noticed any differences in his performances over that time? “One thing that has changed is that I now don't pretend to think something for the sake of a joke. I mean there's always comic exaggeration and embroidering a story to make it funnier, but it's more true to my life now. I used to say I hated kids, for example, and it wasn't true – I've always loved kids and wanted to have them, but that wouldn't have fitted with the style of comic I was earlier in my career.

“I think being truthful makes it more chancy, but if I take an opinion and try to find a way to make it funny – even if people don't agree with me - I think it pays off because audiences know what's authentic.”

His fanbase is, he says, “pretty broad” - people of his own age and above, and teenagers who know him from his Mock the Week appearances, while some of his audience is drawn from from his TV advertisements and occasional acting roles.

Byrne may do more acting as he has some ideas bubbling away for a sitcom – no doubt one about a miserable middle-aged git one of them - and who knows if we'll lose him to the small screen. Catch him live while you can.

Catch Ed at St David's hall, Cardiff on November 29. Call 029 2087 8444 for ticket details.