I'm mostly going to see Les Mis on the 30th (my birthday!) and then catch a two or three other shows while I'm there, and also spend too much money in bookshops, should be fun :)
(also, any advice as to where to go: bookshops, geeky stuff, coffee shops, etc, would be grand. I haven't been to London in ages and the previous times I mostly did typical touristy stuff.)