Has I said before London is a great place to see theatres, there are some very nice shows there. Lot's of people get amazed on how great, and entertaining they are. So now if you would like to get in these great shows you are going to have to buy the tickets early, because if you wait 1 or 3 days before to buy them, they could already be sold out. Many buy the tickets months before, so they can be sure to see the show. Not all shows are the same popularity, so they are not all going to get sold out, but if you travel in the tourist season, then you should also consider the Internet, I myself have not tried it, but people say its easy to buy tickets there.