Hi Tim,
I've recently been allocated onto the August area course, but I think I might have been one of the last ones as I've also read posts here from people being allocated onto courses in October/November.
As a rough indicator I'd factor in about a 6-9 month wait between successful completion of selection (which can take around 3 months itself) and a likely start date at college. You'd have to speak to HR about the possibility of deferal, but I think that as long as you are clear about when you will be free to start at your interview (they will ask you about this) then they will do their best to allocate you to a course that will accomodate this.
I too have heard rumours of the college possibly moving to Whiteley. Not really sure how much truth their really is in this yet, but realistically it isn't going to make a huge difference - it's only about 30 miles away from Hurn and I doubt that if such a move did occur it would have anything less than a positive effect on NATS training and recruitment.