Cancellation charges - change school.
Where I fly, you pay for the time you actually fly. Otherwise, it doesn't matter why you cancel a lesson (although no-one does it at really short notice without a good reason), you don't pay.
Our instructors are all really good, many retired airline staff and our planes are excellent.
Ian, as others have said, if you're not enjoying it, try changing schools. Sure, the weather is a major frustration - has been for me anyway. But, it will become less of an issue with experience and ratings.