From what I understand the exam process is strict at the college, as you would hope considering the number of lives you would be in charge of at the end. If you fail one exam you might get to resit it. Fail it again and you're out. You owe it to youself to knuckle down and work hard over easter and nail the A-Levels to prove to youself that you have what it takes to work hard to achieve a goal, even if you don't enjoy it. It took me getting to university to understand that, and I fear that it might take you not getting accepted through the recruitment process of NATS for you to get it. I had whole modules at uni that I didn't like, but if I had failed them I would have been chucked out.
Imagine the scenario. You leave with a D and an E at AS-Level. You go through the stages and you are fortunate enough to pass and get accepted to college. You then fail an exam twice and are chucked out. What is your back up plan? No university worth going to will accept you, so you're back where you are now, only a year or two older.
I know it's easy for me to say, and I'm not trying to be hard on you. I just take a realistic view on life rather than the dream world that a lot of people live in (not you necessarily by the way). For example I know very few people make it through the selection process for NATS. I would love to get through, but realistically my chances are slim. However, I do have an engineering degree from one of the best universities in the country so I'm not going to struggle to find other work.
I wish you the best of luck but I would suggest finishing your A-Levels, as boring as it sounds. What are you studying anyway?