Just to pick up on BRL's comment.....
If you get the chance to go to D&D at West Drayton - take it.
I visited them last year and I have to say that it was one of the most interesting afternoons I've spent in a long time. They took the time and effort and answered every question that was asked of them.
During my PPL training I never had the chance to make a visit to any ATC unit so I wasn't sure what I was expecting to see. To be sitting at WD watching aircraft bashing the circuit at EGNT was amazing.
The folk that work at D&D do a superb job - you will not be dissapointed with the visit I can assure you.
PD