I don't think Warwick really care about GCSEs. It's only Oxbridge that seem to, Oxford especially. Those GCSE results are fantastic anyway so you shouldn't worry. I got 1 A*, 4 A's, 3 B's, 2 C's and a D at GCSE, which are good results but aren't amazing, and I got an offer from Warwick and am now going there in September. As long as you get good AS results & good predicted grades, so basically showing you can get the grades required by Warwick at the end of A2, and have a good personal statement, you'll be fine.