A lot of people arrive having quietly decided they are not a physics person. That is almost never true. It is usually one specific thing that went wrong early, was never caught, and has been quietly charging interest ever since.
There is no entry test, no minimum grade, and nothing at all to prepare. You do not need to know what is wrong, or bring anything with you — working that out is my job, and I bring the problems. Turning up is the whole of the preparation.
The first hour is free, and it is a lesson rather than an interview.The first message gets a real answer from me, not a sales reply.