"I'm also feeling quite guilty as well as I don't particularly want to leave my parents too far behind because of the help and support they've given me in the past 18 and a bit years of my life."
There's a reason they supported you throughout your life, and that's because they want wants best for you, they will be so proud of you gaining that scholarship and making the most of the oppurtunity given to you. You won't want to look back in the future on something that might have been. Surely the extra little bit of a journey is worth studying the better course, is the 4 hours by train or car? How close are the other 3 Unis compared to Aber?
Make sure you are in contact with the student support at the University, as they can be of great benefit and reduce any stresses that may be on yourself in terms of academic stuff.
The first couple of weeks or so will definitely be very hard it terms of home sickness, but you are only 4 hours away, which isn't really that far. At any time pretty much you can just get on a train and before you know it you'll be home and comfortable. There will be moments of down-ness, and also moments where you'll realise this is what you have needed to do and be happy. Try not to let the brief home sickness moments get the better of you and soldier on.