capries I really think you have to think long and hard about the commute from Kingston to Wally Girls - it is possible but would involve a really early start. Depending on where in Kingston you are you could use X26 bus and then change (possibly at Worcester Park) for the 627 which is the dedicated Wally girls bus. However your dd would have to get X26 at 7am and the 627 is notoriously unreliable.
I think there is someone on the forum who lives in Norbiton and goes to Wally Girls so they may post. Coombe girls is going through a purple patch at the moment and the girls in the top streams do very well. You have a tough decision to make