Hi, I'm sorry to hear that you had such a bad fall as 5 weeks is a very long time especially when its unpaid! I am not an expert but in my opinion horse riding always has risks, the calmest horse in the world can do anything and I think when you get on board a horse you accept those risks. I understand that when paying at a riding school you might expect the risks of riding to be eliminated, but this isn't the case. In order to place blame on the riding school I would say that you would have to prove that the riding scool expected the horse to react like that and that despite knowing you were a novice rider placed you on a horse that was only suitable for an experienced rider. Do you regularly ride at this school? How much did you tell them about your riding experience as the majority of people who ride at schools are beginners and someone who owned their own horse and rode regularly would normally be viewed as a more experienced rider. It might be best if you go and have a chat with the riding school and ask them about the horse, you could also ask others that ride there what that particular horse is like. If it is unusual for that horse then I don't think you will have a case. Good luck and I hope you are feeling better