First of all, I would suggest that you see if you can find a Trec riding club close to you. You can find them on the NHS site if they are registered, like White Horse Trec Group, not sure they go that far down though, but they might have an idea of anyone in that area.
You do need a few bits of specialist equipment, that might prove costly to get together all at once, and the 'low branches' need to be properly marked of course so you get the heights right, but I'm sure you know that already.
I'm too far away I'm afraid and have no time at to spare! Not even joining riding club in January because of time constraints this time round....