I got an A in physics...help

First year science GCSE is literally irelevent once you do the additional science GCSE.

what do u mean?

Do loads of revision and past papers until you are confident. If you're teacher thinks you can do it that should give you a boost anyway.

I'm not sure if they still do it in the new GCSE, but last year we had core science which we did at the end of year 10 and then we did additional science at the end of year 11. They only looked at additional science when I chose my Alevels.