Transferring is really, really easy. Go into your uni GP in Wales and tell them you "want to transfer from your home GP in Somerset" (they will have done this a million times, for almost every student at university there). You will have to fill out a little form with your old GPs address on it (I had little idea what mine was, I made a guess and it worked out fine).
The transfer will be done in a few days electronically, but normally you don't even have to wait, you can see the uni GP straight away if you insist.
No one in Somerset ever needs to know. Your GP in Somerset will know that you are transferring to a South Wales practise though, but that's all.