From what I see form most of the non-selective school prospectus', the general minimum requirement is 5 or 6 GCSE A* to C, including B's in the proposed AS subjects (maybe A for maths).
Application deadlines vary, but it always be before the final GCSE's are taken if applying while in yr11.
In practice, though, many of the external places are going to those with straight A*/A's.
So, is it done on predicted grades / target grades?
If modules have already been taken in yr10 (maybe earlier than they should have been, without the desired results, so retake on the cards) how much weight does this give?
How much does extra CA and other general stuff on the school report get considered?