Helen/HP20,
I was asked my preference for Aero/Area when they called to say I'd passed Stage 3. At that time I asked about courses and was told which one they thought I'd be on and the estimated start date.
A while after that, I received my PIN for the 'Departure Lounge' - a part of the NATS careers website with forums, accommodation info, etc for TATCs-to-be - this also contains *some* of the distance learning material.
About 6 weeks before my college start date, I received my contract.
About 4 weeks before my college start date, I received the remainder of the Distance Learning material and some other stuff to help prepare for starting at Hurn.
Hope that helps - if you want timescales, just ask.