Just a few additions:
Aerodrome is a bit shorter than Area (6 months-ish) as you either get just a Tower rating (for London airports) or you stay on to get an Approach rating (will allow you to work at any regional airport or London Approach located at Swanwick).
You can express a preference for location, whatever discipline you end up on, but no guarantees... If you desperately want to work in one place, consider approaching one of the non-NATS airports as they may take you on (and you're applying to a place then, not a company).