In reply to Justaname:
Spar in Hope do or have previously sold some gas (and other camping bits). Across from the bread perhaps?
But I haven't paid much attention to whether it's the canisters for the car camping stoves or for a backpacking stove like a pocket rocket (etc).
Probably better ring and ask and not rely on my vague recollection.
I think you'd be in with a chance at the other places you mention as well - maybe add the petrol station in Hathersage next to Outside to your list?