Just because there are no JMA members does not mean there are no jet flyers, it just might be harder to find them. IMHO the JMA does not offer a huge amount, particularly for those of us that live out of the 'central' area. I am open to be convinced otherwise.

Some of the larger airports are a bit funny about selling Jet A1. The smaller ones might be better. I am not sure how far Exeter is or whether you would have any luck there?