Wow ...what a fantasic array of in depth resposnes,thank you all very much.

I had no clue this could get so complicated and mired down in red tape.
Im wondering off the top of my head whether leasing the land from the farmer for 500 years for a cash sum would be less of a headache,although i should imagine the change of use problem would still apply.

One point i didnt mention, is that there are towo houses side by side including ours that were built and owned by the farmer (mother of farmer still lives in other) and was built by using some land from the same horse grazing fields.around 40 years ago.

I wonder if this would would make change of use any easier?
Thanks again for the time taken by everyone, keep the responses coming!