London is a complicated web of tubes, trains and buses. It's all quite well connected, but getting from one side of town to the other can take a long time (and likely involve a few transfers of transport lines). The key to success is to group your activities together geographically, so that you don’t have to double back into an area you’ve already visited. It’s also worth investing in an Oyster Card or daypass. Buying tickets every time you get on a bus or tube will drain the pounds out of your pockets at a depressing rate.