Sad to see so many people getting excited about their D's C's and a 'few' B's for their GCSE results, and then believing they can 'take on' college. Passing GCSE's is not exactly the hardest thing to do, and when it comes to preparing you for A-levels, well simply put, they don't.
They are nowhere near as hard, they don't require half-as-much effort, and they need barely any 'private study'. The fact is, if your getting ready to breeze through A-levels just like you did with GCSE's, you're going to fail. Simple as.