If you're embarking on modular training with a PPL(H), then there are no entrance requirements as such just, as you say, a sufficient knowledge of maths and physics.
If you have already undertaken PPL ground exams, you should have a rough idea of the level that is required.
Some integrated schools may have their own requirements however.
If you find you're having difficulty with some of the concepts and you're undertaking distance learning, you may have to put yourself on a brush-up course.
Cheers
Whirls