I didn't realize that refilling propane tanks isn't done everywhere. I can only speak about the US, but here you can get your tanks refilled. There are plenty of places that do tank exchanges too, which I think is what you're saying is the norm in the UK. The tank has to meet certain specifications to be refilled (this was just changed a few years ago, the new ones have a triangular valve knob on top).
1979 Gulfstar 37 Laissez Faire