Hi Nick and John,
the gaslow system uses an external filler of the same type as autogas modded cars and the system is designed to be refillable. I am not sure as you point out as to the legalities of forecourt filling, but to date have never been refused use of the pumps. Also the manufacturers website states that the system is EU approved so I assume that would cover forecourt refilling? Their website is www.gaslow.co.uk
Regards AB