Hello Paul,
Welcome to the forum, please don't hesitate to ask questions or join in with any of the topics.
Your gas question, It shouldn't cost a lot to change.but the cost will depend on what you have already. I'm not certain of the change over date, but older gas systems used to fit the gas regulator directly to the cylinders, in which case all you would need to get is a regulator that fits the fFlogas gas bottles. If you have the newer system, where the regulator is bolted to the caravan bulk head, then you would need to get the appropriate high pressure gas pipes (known as pig tails)and couplings for the Fflogas.
All these parts should be readily available either at your flow gas supplier or caravan dealer and I guess the cost should be under £50.there might fitting charges - consult your dealers.