We have a lot of small plants in the greenhouse so trying to be ahead of the game we bought a heater for it.
It does not seem worth the money to install an electric cable just for the few days and nights that heating will be needed. Particularly as it will have to be installed by a registered electrician in a protected sleeve etc.
I thought paraffin was cheap but was it? It seems to be dearer per gallon than petrol or diesel now.