Family seeking accomadation for five

I am looking for accommodation in London, preferably in Zones 1 and 2 . However, we are also interested in outer areas that are close to tube stops. We will likely be staying for the entire two weeks of the Olympics.

We have five in our family: my husband, his sister, his mother and father, and myself. We are non-smokers. Our ages range from 25-52, so no teenagers or small children will be accompanying us!

We would prefer three bedroom accommodation but can settle for two bedrooms with a sleeper in the living room if necessary. We are on a budget but its not too tight, so we are open to reasonable prices.