Stress about meeting offer

For reference i got an offer from Cambridge of A*AA, but i am completely terrified about not meeting the offer conditions in the real exams, i recently had my mock exams and got A*A*A* but im afraid that i might mess up the real ones and it is panicking me out of revising (i know a juxtaposition) but any advice?

And yes i know im lucky to be in the position i am but even so

I feel in a similar position and I keep reminding myself that I wouldn't have been predicted the grades to meet a Cambridge offer, nor would I have even got an offer, should have I not been able to get A*AA in the exams. The fact that your mocks went so well obviously shows that you're more than capable of meeting your offer. I get your fear about something going wrong in the real exam which means that you can't perform your best. The best way to move past that is to do everything in your ability to feel prepared when you get into those exams. Do the past papers, bombard your teachers with essays and extra marking, talk to them if there's a particular area of the spec that you're not feeling confident with. They want you to do your best in the exams and meet your offer, even if that means a bit more work for them.
There's not loads that you can do to get over that "what if" feeling because, quite honestly, it's hypothetical at this point. By channeling that fear into motivation, you should come into your exams and find that they all go brilliantly because you've prepared yourself for whatever could go wrong.