Well to answer that question, yes there is an 'Approach Only' option, you would be destined for TC and live out your days working either LL,KK,LC or Essex.
You would still require the ADC option at college as that gives you the background required to operate APC.
I may be wrong as things change all the time down there in gods green land but the quickest way out of the college is to do ADC and then sent to one of the London ADs, you would effectively do the one module then go to one of the above airfields (after 3-4 months I think). Tacking on APC would be next (adding another 3 or so months)
If you ended up doing TC then the ADC part of your student licence would eventually lapse.
Then the long un is Area.