A thing to watch out for near Aylesbury is where the route of HS2 will run which will run.
The countryside to the west of Aylesbury is glorious with lots of lovely walks. And Waddeston Manor.
My DD1 lives west of Aylesbury and my DGDs are doing well at their schools and they still take the 11+ in Buckinghamshire, although its optional. DGD1 decided not to put herself through it as she wasn't likely to pass (she thought).
Thame is over the border in Oxfordshire and is really lovely and in a good school catchment area. Haddenham Primary school is much desired I believe,. I think, like most country schools, most of the village primary schools are Church of England voluntary aided. There's also a very good riding stables (Hartwell stables, at Westlington)!