Thank you, Kirsten and Colin, and for the kind offers have I have received. At the moment, I am just trying to weigh up my options. (D'you see what I did there?)

You might all be interested to know that Karen from the Grantown-on-Spey Caravan Park just told me that they stock gas cartridges at their shop.

I was going to mention that there was a caravan site. There was a hardware store, Donaldsons, on the main street. According to Google maps it was still there in Sept 2016 with a big Calor Gas sign in the window.

A friend that works in Grantown suggested Donalsons. Their number is 01479 872798. It sounds as if you are sorted though.

Hi Emma
I live in Grantown-on-Spey and have just checked in Donaldsons. They have Gaz, screw type and the ones that look like aerosols. The smallest screw type is the 220g size. Hope that helps.
Any other queries about Grantown do get back to me
Mike

Thank you, everyone, for your kind help.