To get back to the original post, I've used AirQuiz and, in my opinion, it's the dog's danglies and well worth every penny.
I've done more Met courses than I can remember and passed more Met exams than any human being should be subjected to, but it's one of those subjects that I have to learn every time, nothing stays in my head longer than about an hour when it comes to Met.
Good luck, you'll get there.