I use bogstandard propane , I get it from where ever is the cheapest wether it’s got outdoors , screwfix , B&Q , where ever . Only thing you do need to remember is a few drops of silicone oil before you attach the filer nozzle as green gas has oil in it but propane doesn’t .
i ‘think’ it’s illegal to refill small gas bottles (I’m sure the truth will out soon enough) but plenty do it , it’s like the Baofeng radios your supposed to have a license to use them but hardly anybody does have one .
in no way shape or form am I condoning the breaking of any laws , but it happens ! 😇