I know what your talking about, I'm friends with a lady called Bunty, she is english and came to Australia a long time ago, been riding all her life. she was instrumental in establishing Pegasus in canberra, which is a riding for the disabled place. she used to run lessons and really got it going, would get the riders out and about playing games, etc. she had to leave for a while, and recently she went back to vulunterr, apparently it has all changed, all they do is lead them around the indoor arena in endless circles. she was told of because she wans't 'leading the horse correctly' and she tried to play games with the riders, take them out of the arena, and they ended up kicking her out, even though she was pretty much one of the founders. a lot of the problem nowadays is with insurance, and also people in charge who either don't understand that people with disabilities are actually very able, if you give them a chance, or they are simply stuck in their ways. I think your best bet would be to try and find someone who would be willing to let you ride their own horses, away from a proper institution. obviously someone experienced, with a quiet horse. I would love to do it, but I live in canberra and don;t have much time at the mooment, but i know there are plenty of people who would jump at the chance to one get their horse excercised, and two help someone else discover the joy of riding :] good luck, I hope you find what you're looking for!