Have a look at the course content and if there are any areas relating you feel you are weak on, then maybe just refresh them in your head. For Example, I am beginning a Comp Sci degree, so I am brushing up on my Maths and doing an intro to CS course online - which definitely isn't necessary but I would like a head start when it comes to September.
You could contact the university and ask if there is any reading that would be beneficial to do over summer.
Also, enjoy your summer!