Kind of a tricky one. There aren't traditional memoirs or autobiographies by him, which honestly fits his vibe. He was so private. The closest you get is the collection 'Tigers and Cheese', which isn't a linear life story at all, but it's built from his stand-up and panel show bits. Reading it, you piece together fragments of his worldview—the mundane jobs, the absurd takes on family life, his complete disdain for gardening. It's a biographical mosaic, not a portrait. You learn what he thought was funny about existence, which in a way tells you more than dates and places ever could. I found myself reading it in his voice, and that's the real life story right there, the voice.
Searching for a straight biography might leave you frustrated. I saw someone on a forum once really angry that there wasn't a proper book about his childhood and career path. But that feels like missing the point. The material he left behind is the exploration. The chapter on his fictional holiday rep persona tells you everything about his feelings on authority and boredom. It's all in the subtext.