There is a shortage of AREA controllers at this time. Therefore you are, as you say, more likely to be posted to Swanwick.
If you are sent along the ADC/APC route, the powers that be will decide where you are to be sent.
Don't bank on going where you want, as it probably won't happen (Unless you like Swanwick!)
Airports like Cardiff can be poplular, therefore staff with service may get preferential treatment over Students.
Someone correct me if I am wrong
Don't let this put you off though!