Can you get your $ back? Heck - it sounds like you should be teaching this class.
You can get the distractions you want for training by going to the park. It sounds like you have been doing such a great job that you are ready for that "very reputable dog training school" NOW! Give yourself credit for all that you have learned and worked hard on.
Do not think you have to be at a certain level of learning for that school to take you. They should welcome anyone at any stage of training - it should not matter where you are in your training for them to be helpful. The point should always be to educate the person so that the dog has the best environment possible for successful learning .
Love Them & Lead Them,
~Elizabeth & Doug
Dog Training the Way Nature Intended