Should I re-take my gcse's for Medicine at Cambrdige?

I should add that I haven't got my GCSE'S, but am waiting on my result. If I achieve what I was targeted, I am looking at a possible 5A* 2/3A's and 3B's. My A-level choices are: English, History, Biology, Chemistry and Maths, and I am determined to get at least 3A*'s. I've already started revising and taking some past papers- I know I can get these results. I appreciate that my GCSE'S aren't as high, as I do not want to disadvantage myself in my application- should I sit 2 of them again to bring it to 7A*'s? Any advice would be extremely useful!