The answer to your question
I used to buy Air Total fuel at Dunkeswell. Due to a problem with the fuel I now bowser down to Exeter and buy at .98p per litre plus vat
Problem with Avgas you need an ADR licence to tow more then 333 litres on the road ( before you ask I have one ). Have tried CYMA but was not happy with the some of the things I have heard about their delivery chain ( rumour only, but with some substance)
Jet is different delivered to home at .36 p per litre