I haven't really kept track of fuel usage, but last September I left home with a full bottle (Trangia fuel bottle, 1 liter), camped at the National (Wed-Sun) making tea (that kettle is quite efficient!) and morning/evening fryups, and got home with roughly half a bottle remaining. It's not
that inefficient, and at least you can easily see how much you have left compared to a gas canister.
Between the set and the bottle a Trangia is a bit bulkier than others, but I've seen how most people camp, I doubt that's really the problem.
As for fuel availability it depends on where you camp. I've never actually had to buy the stuff in the UK so wouldn't even know what it's called, but in the Netherlands literally any supermarket will sell it in the cleaning isle and I'd be surprised if the UK is much different. (Muslim countries possibly not so much as they can be funny about alcohol, even if it's the non drinking kind, but by then you're a fair old way from home.)
Refilling is easy if you use the special fuel bottle. Though do make sure it's not still burning. I always use the moderator when cooking (as opposed to making tea) otherwise it'll be too hot. It's a bit of a faff and you want to have something like a Leatherman handy because you won't be touching that with your fingers if you want to adjust it.
Camp stoves are kinda pick your poison whichever you choose...
Trangia is nice and quiet, easy fuel availability, and a good complete yet fairly compact set, also good for indoor/in-tent use, but flame control is a bit cumbersome.
Petrol stoves are always kinda dangerous living on the edge, definitely outdoor use only, range from quite noisy to upended rocket engine, fine control can be hit and miss (or entirely optional) but they boil water like nothing else in any weather and you've always got plenty of fuel with you.
Gas, the cans always run out and are kinda shite when it's cold, but otherwise it's dead easy and the cooking experience is most like cooking at home.
Jetboil specifically is perfect if all you want to do is boil a cuppa, and if not, not.
I haven't met anyone yet with an electric stove...