During A-levels, i had too many problems so i was never the type that got work done. So, when it came down to the exams I had to learn everything on my own within a short period of time.
For my A2 history exam I got A,A,C. For the two A grades i revised only 3 days and managed to get high A's. Whereas for the C grade i revised only two days. For As Psychology I revised literally 2/3 days for each module and managed to get A,B and a C. For english, revised 3 days for each and got 3 A's. If you are the type that can memories quite alot of information, youll be fine, Seriously, i found self teaching much more useful than going into college and listening to the teachers...