Hi Calpal,
I assume you're getting close to going to the college - NATS circulates the accommodation info via the 'Departure Lounge' thing on their website - you'll be sent details of how to access it once you've passed everything and the medical too. HR set that up, so you can always contact them.
I don't know of any student accommodation website as such, and the accommodation list clearly states that NATS does not endorse any of the accommodation - it's up to you what to do and what it's like!
Sorry I can't help more...