Like others have said, training at Whiteley, CTC, will not guarantee you're doing an area course, but going to Gloucester will guarantee you're not doing an area course.
It depends how important it is where you spend your career - doing area will mean you can only work at Swanwick or Prestwick and only for NATS too as no one else does area control in the country. An aerodrome only rating means you'll be working at one of the London airports as they're the only ones that are tower only, I think and of those London City is at Swanwick as well. Doing aerodrome and approach means you'll be sent to wherever you're needed after finishing the college - that's based on business need and your preference might or might not be taken into account and that can range from Southampton to Aberdeen and lots of places in-between. However, Aerodrome and/or approach does mean you can take your validations elsewhere if you want to as there are plenty of non NATS airfields around the country.