For medicine you may be a little lower, but they're well within the range of consideration and provided you do well on the relevant admissions tests, there's no reason to suppose you don't have as good a chance as anyone else.
For any other subject GCSEs are largely irrelevant, particularly as you will have exceeded all the minimum entry criteria in terms of English and Maths, with the exception of UCLs language requirement (which you can complete in the course of your degree).