Many thanks to all the kind members who have advised me in this matter. It looks like I will be leaving BT soon.
As others have suggested there are a number of independent companies that will provide advice on Satellite or 4G broadband solutions that might meet your needs: try a bit of Googling.
Managed FTTP On Demand services are available from companies such as **Edited** but as others on the forum have mentioned there is a non-refundable survey charge of £300 and the fibre installation charges may be significant as it depends where the nearest fibre aggregation point is located, not the BT Openreach FTTC cabinet.
I would also write to my MP complaining of the lack of broadband availability
Good luck finding a reasonably priced solution.