Bottled Gas
This can be LPG, propane or butane.
Butane is a bad choice. The vapour pressure drops below 7C. This means that it turns from a gas to a liquid and therefore is not under any pressure. You won’t be able to use it until it warms up which might be in spring. Also all the regulators vary. Very frustrating!
Propane is good to -20C. It’s a heavy gas that means it concentrates low down and can explode if lit. Always keep bottles in a low compartment with holes at the bottom.
Both bottled butane and propane can cost £4 a kilogram, depending on bottle size, whilst LPG is 70p per litre when you buy it at a fuel station, even though it has some fuel duty included in the price. You can buy LPG adaptors online.
If you are in the UK your LPG tank will need a bayonet fitting or an adaptor . Like this one.
Fuel station owners don’t seem to like you filling up LPG bottles so it’s best to keep the bottle in the boot of a car. That way they think you have an LPG car. Then pay for the LPG. If you want another fuel get that afterwards, and pay a second time. It is best not to drive the vehicle without paying for fuel. They think you are doing a runner.