Okay. So we need...
Nice 3 bed (flat/masionette fine)
Close to tube/train
Good primary school
Nice area where we might make friends, find groups etc.
Shops, cafes restaurants.
Would prefer South (where our friends area) or West (easy to get out to see family)
Think I might be very optimistic to think it's possible for us to live in London for a few years but you're the people to ask. Basically area is (almost) more important than space.
But with 3 dds we do need to be able to live reasonably comfortably.