A degree will (probably) not help you much in becoming a pilot. It would be a VERY good backup if aviation fails.
However you are young and I'm sure you can adapt. If you are set on being a pilot - why spend a lot of time and money (student debt) doing something else?
My thoughts are, get on with what you have started - your A levels and be sure to do well at them - put 110% in all times. Then when you have them, get the highest paying jobs you can get - yes 2 or three at a time and save every penny. You can probably get your PPL in less than a year doing this and be credit worthy in your own right. Then maybe part savings and part loan to do the rest needed for fATP.
Simply set your goals and put EVERYTHING into acheiving them. I'm not saying it is easy, but if you live and breath every moment for what you want to achive, you will do it.
These are of course only my thoughts, but I wish you all the best whatever happens.