I recently had a one-year break after I left my old job and was held to my one-year 'non-compete' clause. I spent the time working through all the things in London I hadn't seen, and have now pretty much done the lot. (The Fan Museum in Greenwich remains unvisited, but near enough!) There is a lot of interesting stuff at the smaller end of the tourist attraction list, eg Keats House, Freud Museum, Fenton House in Hampstead, 2 Willow Road in Hampstead, that most Londoners, let alone tourists, never get around to seeing.