Are camping gas stoves allowed? 
Yes, but only if used safely and correctly.

Do not use any cookers inside a tent or near the entrance – use them outside your tent and well away from your own and other tents; wait until gas cylinders are completely empty before changing them and do not change them in a tent; turn the appliance off after use; no naked flames inside a tent.

Gas cookers insider camper vans and caravans should be safety tested and gas cylinders kept outside the van which should contain a fully charged water or dry power fire extinguisher.

Go to 
www.fireservice.co.uk/safety/bbq for further information on safety