Open the file on the left hand side. Follow the instructions to join Isaac Physics and the physics course prep class using the code given. Then work your way through the assignments over the summer. Enjoy and we will see you in September all primed and raring to go.
Apart from making sure you're really confident with your GCSE work, another very good thing to do over the summer is some reading.
Here is a suggested reading list. Enthusiasm for a subject is very highly regarded at university interviews, and it's never too soon to start (if you haven't already that is!)
Many of these books are available very cheaply second-hand online, or try your local library.