blackbatz,
Oh, meaning you are going to do a day trip to Paris for Lourve museum?
I haven't watched any musicals (cos poor student that time). But I heard that if you go to the Box Office early in the morning, they usually sell same day tickets at very attractive discount, >50% discount.
Oh yes, museums at London is GREAT and it's FREE!! If you are into paintings, you have to visit the National Gallery, excellent collections, no Mona Lisa, but have many other Masterpieces of the great artists. we usually spent one whole day there. British museums is big, and the collections are very good too. And so are other musuems.