just wondering where she is likely to sit Bucks exams & when we'll find out?
It will be a Bucks school, but you won't find out until quite close to the test, I'm afraid.
Also whilst I know we should put favourite school first on the form etc how does it work if first choice is a Bucks GS & second is a Herts semi-selective school, & third is another Bucks GS, Bucks Upper etc? Do the LAs really liaise or should we put the Bucks schools first then Herts (I suspect not but would appreciate reassurance!)
Yes, the LAs do liaise, and Bucks/Herts seems to work very smoothly. You should always put the schools in your real order of preference
. If that is alternate Bucks/Herts schools it doesn't matter a bit.