wouldn't worry to much matey, you can always do a resit. Even if you don't get the grades you was hoping for apply to the the uni you want to go to during clearing at the end of the summer, chances are they'll still take you on as they'll want to fill all the spaces up. Its only in the very popular courses that they can afford to be picky.

the teachers only tell you you need C+ grades to get into uni as it makes the school look good (pass rate) a mate of mine got into one of the leading uni's in London and he got all D's

Do they still do the level papers? low/medium/high?
when i was doing it if you did the lower papers you needed to get a high score to get a c+ grade but with the high paper you didnt as it was a much harder paper