A-Levels Anxiety

I am currently finishing my A-Levels, I have 4 conditional offers ranging from BBB to AAA and I have predicted ABB. My AS grades are BBB and I can't stop panicking and thinking that I won't be able to maintain or increase my grades. I suffer from anxiety and have had a couple of rough years where I have faced several mental health issues. So even tho everything seems better I can't stop thinking about the worst possible outcome. If I am not able to achieve said grades for my courses is it possible they will provide me with the option to do a different but similar course and if not are there usually many options during clearing?

When you refer to "the worst possible outcome", do you mean Clearing? Being in Clearing is not the disaster which many people assume it is. It just a process whereby students without a place are matched with universities / courses without places. What's so awful about that? There are normally plenty of course to choose from.
You can alleviate the stress a little, and make Clearing not seem as bad as you clearly do right now, by doing a little research ahead of time. (The only real issue with Clearing is that there can be limited time to make decisions, so doing the research just-in-case can help there.)
So look around for universities which would accept BBC, perhaps, or even BCC. If you were to pick from these, which would you choose, and why? Can you see yourself at one of these universities (if your A level results required it). Once you're in a position where you have a Plan C, then Plan A (going to your firm choice) and Plan B (going to your insurance choice) going wrong doesn't seem so scary.
Good luck!

What I mean is not being able to have a spot in one of the courses I chose and not being able to find a course elswehere. To be honest I only know the minimum about clearing and should do some research on it. I am 2 months away from my exams and anticipating any type of suffering I could have, I was diagnosed with depression 2 years ago and this is all a bit too scary because I was already on track and being able to focus on my goals.
How long does clearing usually last, I ask this because I know a friend that got into a course with foundation in the end of September...
Thank you for the advice, I will make sure to look at some courses with those said requirements.

Last year, 38140 UK 18-year-olds secured a place using Clearing - so there are clearly plenty of places available. (source)
And that figure is only for the 28 days after results day. Clearing itself doesn't close until 21 October this year. (source)
It's natural to be anxious. Which is why I suggested you find out a bit more about the process, and where you might to go if you end-up in Clearing. It'll make the prospect seem a lot less scary. (And, obviously, hopefully you won't be in Clearing anyway!)

Thank you a lot for all the advice