It's probably best to start with the official channels here - there are certainly some good bargains to be found if you look privately, but there are also a lot of people who are looking to rip you off, so the safest way is probably a dedicated website or tourist information centre.

If you go to visitlondon.com you will find a good range of accommodation types whether you are looking for hotel, B & B, camping, self catering etc. The official Olympic provider is the Holiday Inn, so it's a good idea to check them out as well. It is advisable to start looking now, as a lot of places will be fully booked already. You may find you have to be flexible if you don't want to pay a great deal of money - eg, think about different accommodation types or consider staying further away from your preferred venue. if you click here you will find information about how to reach the different venues by public transport, which may help you to plan your stay.