Worried, Oxbridge Econ

I didn't do brilliantly in GCSE's for context (9998876554), but I'm actually going insane for A levels, I'm working at an A* Level in Maths, Further Maths, Physics and Economics. I've finished A level maths already and Im halfway through my other subjects. I'm confident I'm going to cook because I'm smart and I have work ethic but I'm scared because I screwed up on my GCSE's because I was irresponsible and it's my dream to do Econ at Cambridge.

If anyone can give me advice, especially what I can do now because I have the talent and the determination but I'm stuck about what to do and I worry my GCSE's have knocked me out entirely from consideration (i resat one just now I think I'll go from a 5 to a 9 in english, the other 9/8s are stem and business).

Thanks in advance