i think the legal side has been well covered, however, you say about needing to be there the whole time for the horses and being out late at night etc - wouldn't it be better to stop doing this and get a job so you can afford to live somewhere and provide a home for your son with his special needs? Nobody is making you look after horses 13 - 14 hours a day. You are not getting paid for it, I presume you are living on benefits so in effect i am paying for it. You don't mention how old your son is but if he is old enough to be at school, then you could work. If he's not old enough to be at school, what do you do with him while you are hand rearing ponies? Who looks after him when you are out at all hours of the night?
I know i sound harsh, but i am just thinking of an alternative way out of your problem, as from the other threads it seems unlikely you will be living there much longer