Hi
Do you have a 240v splitter? ie. can you connect to 240v at a camp site? If you do then you could connect a 240v heater.
Otherwise you will be looking for a LPG heater as most heaters use diesel. However again, there are some chinese versions that come with a little diesel tank where you can buy red diesel (no VAT on that) and use it
Sample here: https://www.ebay.co.uk/itm/142942440753
As you will see a tiny plastic bottle where you add the diesel.
I don't know what these are like, this is not a recommendation, i have seen many camper owners who have these and seem pretty good. Please research.