I was in your position (like many others I'm sure).
I didn't think the airlines would be all that keen to take on a 21 year old boy with no life experience and only A levels. I say 21 as that is the minimum age to sit the ATPL exams.
You're 18 when you finish school (A levels) so you need to find something to do for 3 years. I did a degree that put me in debt but gave me great life experience, met some great friends and above all puts a couple of letters behind me name.
Having a BSc will/should get you a higher earning job, I also did IT (Multimedia Tech & IT studies) and I found my job nearly 2 years ago. I saved enough to do my training in no time but fell into the rat race of getting my own place. So I've had to start saving from scratch again.
I'll be going modular with BFC in Bristol (or that is the plan after many years of research) and Ideally I'd like to get my CPL debt free and then a small loan to pay the rest (Multi-IR & MCC).
People will tell you having the degree is pointless and just added debt, but if you take out the maximum student loan and not spend it on drink and socialising it'll come in pretty handy wen flight training begins at 21/22.
So the choice is 21 no degree and a fATPL or 22 with a BSc and a fATPL and a back up career should it go pear shaped
Don't bother with the RAF if you're not 110% committed, they'll figure you out in no time and you'll waste your time and theirs. As for Integrated v Modular ... that's a personal choice.
Good luck.