Ok got hold of the books now.
CAP 682 part 6
para 2.2
The majority of organisations seeking approval from Authority will be based at an aerodrome in united Kingdom. How ever JAR-FCL provides for the use of alternative base aerodromes and for arrangments to be made with other training organisations. Where arrangments are made with other organisations, these shall also be approved in accordance with provisions of FCL 1 and 2 and shall be accessible for inspection. The Head of training of the FTO making the arrangments shall be responsible to the Authority for training standards and for compliance with FCL in all of the organisations at which parts at which parts of the courses are undertaken.
So its a paper work exercise as long as the alternative base is already approved for SEP ppl training and no other fees / inspections are required.
I have heard of cources being run away from the FTO's listed. So it can't be to difficult or expensive to do.
MJ