A smart boss will not just look at 'good' GCSE and A-level results. All they demonstrate that within a school environment the person sitting in front excelled. Schooling, despite getting good grades, didn't really teach me much. Being good at school isn't an accurate way to measure someone for a working environment. School is very much 1 size fits all, and most good employers understand it's a load of bullshit.
Unless you have a very very clear career goal, your results are not much more than an ego booster.
I certainly don't need some teacher telling me whether my writing is good or not, whether my maths is bad, whether my knowledge or history is good. I can do that for myself.
So if u did **** up, don't worry.... it's all bullshit