Dude,
An airline pilot is probably one of the few well paid professional jobs now where a degree is not essential, nor even hugely beneficial (when entering the profession anyway). But, a degree gives you many options if you fail or give up on flying training, lose your medical, just decide you don't enjoy flying so much after a few years, etc. that don't exist for somebody who ONLY did ATPL training. An aviation based degree also offers a great many professional options within aviation apart from pilot.
A further consideration is that the services do now generally prefer incoming officers (which other than in the army, includes all pilots) to have a degree. With regard to how people are treated in the services, expect to get treated like the smallest naughtiest schoolkid for about 6 months of basic training, and with moderate suspicion until you've shown more experienced colleagues your worth respecting. If you can live with that, the rest of the career you'd be treated like the important and highly trained professional that you would have become.
Do search on Pprune for discussion on other degrees. Personally I have a degree in Aeronautical Engineering (like a lot of other people round here), which hasn't prevented me or them gaining professional flying qualifications, but also allows many of us to do a lot of other professional jobs (specialisation is for insects !!!) with aeroplanes that other degrees wouldn't have. It was also a LOT of very hard work. At your stage, so long as you at-least pick maths and physics at A-level (pretty much compulsory for most of what you're likely to want to do) the options are wide.
I have an acquaintance, just as an example, who did an aero-eng degree, joined the RAF as a pilot, failed his Hawk course, and last I saw him was a very content squadron engineering officer looking after 20 or so Tornados.
Best of luck,
G