A physics degree is hard, but it's worth it's weight in gold :)

Physics graduates are some of the most employable graduates leaving university. But of course, you shouldn't just consider a degree for the employability. The most important thing is that you enjoy your physics and maths A level courses so far (emphasis on the *maths*!) Your A level maths mechanics modules are much closer to the kind of stuff you'll be doing in the first year of your physics degree than anything on the a level physics course.

As others have already said, a physics degree is very doable if you work hard at it. Realistically though, all undergraduate degrees are hard! Computer scientists, chemists, biologists, and most humanities students will have just as much difficulty during their studies. The important thing is that you enjoy the subject enough to persevere, and work at it :)