Hi there
I would also strongly recommend sitting the ground school at Oxford. The work is extremely intense and the instructors are fantastic!!! They all have their unique individual ways of getting their point across. They have fantastic teaching aids and each and every lecturer is a character!
I have visited many other FTO's and can say without a shadow of a doubt that Oxford is the best by a mile - so much so that i am currently studying there on an APP course
What ever you decide to do i wish you the very best luck!
Regards
Bozzato