Caz - sounds like you'll be glad to get out of there!!! If you look in the classifieds in the H&H they have a list of horse transport people, might find one for your area there
Alternatively, ask if you can borrow a trailer. Even if it's from one of the people on the yard, tell them you're going out for the day, and will return it later!!!
So are you giving him Equijewel? Agree with the high fibre - little and often to start with if possible. Another really useful high fibre feed is Allen & Pages Quiet Cubes - they have linseed in them so help with condition.
That and the aloe juice in his feed - I would double the dose for a while. It won't do any harm or interact with any other drugs but will help to heal his gut and reduce any acid that is splashing around and irritating it.