I have moved your topic to the Bucks forum.
I suggest you start here, with the Bucks CC school place finder:
https://services.buckscc.gov.uk/school-admissionsRLS is your catchment GS, but you would also be within the range of the three Aylesbury grammar schools, based on past allocation distances.
Your fallback alternative (non-GS) school is probably Sir Thomas Fremantle, highly sought after if the number of first preferences is anything to go by.
Take a look at the "Sticky" posts at the top of the Bucks section for more information.
(x-post with Guest55)