" I have been told by my solicitor that there would be know problem as the buildings had been there long enough to be exempt from planning and would just have to be listed accordingly in any contract. My concern is that I intend to use the buildings to run my business from, does anybody have any experience with this type of situation or know whether the planning authorities would object to me operating my business from there (its not heavy industry, I practice sports massage)"
You cannot be compelled by the Local Authority to pull down the buildings. Nonetheless, thay are unauthorised, and, technically, if they burn to the ground, your insurance should not pay out.
In my view, you would need planning permission for user as a business - its not just a question of putting up a sign and just starting. Because the buildings are unauthorised, you may not get that pp - you really need to talk to a good local architect/planning consultant for real clarification on that point.
The fact that other people run businesses from their homes without pp, is no reason to ignore responsibilities.
So solicitor is right as regards building cannot be pulled down. And its not clear whether you actively sought his advices on user - but, in any event, you should get proper planning advice and it is better to look for that from someone other than the Local Authority.
mf