I wouldn't even think about it. I was predicted and have been getting A* in all of my subjects at GCSE. However, I had school issues last year with depression and bullying and I started school refusing, so those grades are gone. The most important thing for me is an A at physics at least ( I already did maths ) so I can go to my chosen sixth form (its all maths!). Don't worry. Universities like Cambridge, I emailed the admissions at Trinity cambridge, don't even care about GCSE's at all because it all depends on A Levels and Interview and any extra tests if necessary.