Perhaps changing degree would be a better option right now, it would make you happier in yourself and if you achieved a decent grade it would give you a confidence boost, and flying is a lot about confidence in yourself particularly on test days.
Your A-Levels won't matter, but they may be an indication that you don't know how to study properly. You may be passionate about flying, but air law and gen nav at ATPL are very difficult and dry subjects (although I personally loved Gen Nav and hated Met, hating gen nav is more common). You will need to figure out what stopped you achieving your full potential at A-level before you invest in this. I personally didn't achieve my predicted grades at A-level, but did ok. Never went to uni, but straight into work. Once I got into flying seriously, and had my balls busted numerous times by PPL instructors for not studying, I finally got my act in gear and got a 93% average on ATPL (not boasting, it's not that hard to achieve).
On the subject of finance, if you're starting from scratch it will be a lot of hours at waitrose before you have saved enough, certainly more than your 4 year estimate. You need to figure out the costs of each stage, break it down, come up with a time line and figure out exactly how you will fund it. It's pointless just getting your CPL/IR, you will certainly need to fund a type rating or bond, and possibly find money for an instructor rating too. Big loans are fine, but when you're unemployed or just scratching round for 2-3 years the repayments will soon add up.
Last edited by RTN11; 22nd Oct 2012 at 20:06.