The allocation profiles for Bucks are here http://www.elevenplusexams.co.uk/school ... n-profiles
For Bucks schools you first have to get 121 on the 11 plus, and then the admission criteria applyx - if there were enough places you would get a place, however far away you lived.
Burnham Grammar usually goes to "all offered" and JHGS and some others did this year, although I think this is unusual. I don't know anything about Berks vs Bucks but others may do. It would be a pretty difficult journey from Ashford to any of the Bucks schools, but particularly JHGS, Chesham etc. There are lots of people on here who know a lot more about these things than I do, I just saw your post and thought it would be nice to answer!