Year 12 predicted grades

Hello everyone,
Im interested in applying to top universities for computer science and my a levels are Maths physics computer and ive self studied content from further maths.
My year 12 mock grades are
Maths - A1
Physics - B3
Computer Science - A3
1 is the upper boundaries, 3 is like scrape the grade
For context ive been very ill for the past couple of months so I've missed lots of school lesson, therefore I near missed the A* in maths this time however I usually get A*, physics ive went down a grade but computer science was the only one which improved from B2.
May I please know how I can improve these my predictions? My current plan is to revise plenty to do well in September mocks which have a chance of changing predicted grades and maybe asking teachers for opportunities to show my improvement such as topic tests.
I strongly believe my first exam day(physics and maths paper 1, physics only had 1 paper and maths had 2) was a very bad off day because in my practic papers in the lead up I was getting above 95% in maths and atleast 68% in physics which translates to A*s and high As.
Obviously this doesn't mean anything meaningful if i didn't replicate it in the actual mock so I want to just prove myself and not make excuses.
If anyone has any advice it'd be much appreciated!
Thank you for reading and have a great day 🙏

You’ve identified the most important thing, which is asking your teachers for feedback and using that to improve your performance in the September mocks. Catch up immediately on the lessons you have missed! You can use the summer to revise and consolidate Y12 content so you’re in the best possible position for your next set of mocks.
You need to prep for bad days when you’re revising. I used to do a practice paper the moment I woke up (so like half-asleep), or do one with noise in the background to replicate bad test conditions. Don’t use actual A level past papers for this (save those for later practice!), but perhaps AS papers or old-spec PMT papers. Like you’ve mentioned, it doesn’t matter how well you do throughout the year if you don’t perform on the day of the exam — that’s exactly what A levels are like.
Best of luck and I hope you ace your September mocks