I wouldn't even bother going home on the 14th, 15th or 16th of December. I mean, I got the 5:30pm train home a few weeks ago on a Friday and people couldn't even get to their reserved seats because the entire train was quite literally full. People were stood all the way down the middle isle all the way to Machynlleth where two basically empty carridges are added to the train.
That was on a normal Friday.
Now imagine a Friday where pretty much the entire university has broken up for Christmas and is trying to get home.
It may transpire that you will be able to go home a day or so or maybe even an entire week early. I have checked my lecture dates for this year and it turns out my last lecture is on the 5th December with my last seminar being the next day. Its worth finding out if you will be able to leave a day or so early because you will essentially miss all the fuss.
Also, I know this didn't happen last year but in my first year I also was able to finish early for Christmas and it turns out that the actual end of term co-incided with some pretty awful weather where some people had a lot of trouble leaving Aberystwyth with train delays and bad roads in an out due to snow etc.