If you do shop, don't forget to take a copy of your passport with you since you can get a refund of the VAT (17.5%). Most of the larger stores have this service, however, there is a processing charge of 5 Pounds so combine all your receipts from that store.

I actually don't find London to be horrendously expensive. Meals certainly aren't if you stick with the more average places (dinner is usually around $15-20 per person). Hotels are quite expensive but not nearly as much as Paris, Rome, Venice.

If you do look for the 1/2 price theater tickets, make sure you go to the "official" one which is in a concrete building in Leicester Square itself since all of the other ones are commercial ticket agents.