Hi Maxwell,
Getting permanent status for a dwelling when involved with equine is harder than when to do with an agriculture dwelling. Not that it isn't possible though.There's quite a few cases of determined folk who have suceeded against planners in being able to permanently reside on equine holdings.
If you were to go down the agricultural route you would be better off going down the precribed route of using the regulations as afforded by the General Permitted Development Order as alluded to in an earlier post. However, to make use of that you would need a holding of 5 hectares some of which you would have to own (although you can rent a fair proportion of your holding on a farm business tenancy).
For your immediate future, moving onto your friends land and residing in a mobile will have the local enforcement team on your backs as soon as they find you. They aren't permitted to carry guns or come with paid muscle,,, so its all basically legal stuff. It can several years for eviction to happen but be warned it could be under a year if planners are on their toes and you don't know what you are doing.
To be clear, I am an agricultural planning consultant but I do agree with Robert Wadell. If you have the time and confidence, all the information, rules, regulations, planning cases and case law are freely available on the internet for you to study. Where I might differ with Robert is that people employ planning consultants to carry out a job for them and employ their expertise just as one may employ any other person to do a specialised job for them.
Good luck which route you take
