My eldest son did his degree at Cardiff,and has never come home since!
He used to travel up from Taunton, lots of trains, some you have to change at Bristol, but lots go straight through.
We used to stay at the Ibis hotel, or the Big Sleep.They are within walking distance of the Uni. The Travel Lodge is quite a way out.
Wear comfy shoes, and take a brolly, it always seems to rain in Cardiff!
Any other help we can give,let us know.