I'd definitely support the "don't use an LPG heater" comment. In fact I'd stretch it to don't EVER use an LPG heater. Dreadful things, which not only cost more to run (yes, I've done the calculations based on cost of available gas cylinders vs. cost of electricity) but the amount of water vapour is appalling, as well as combustion fumes. Oh, and they're good at helping tower blocks to burn down. Its sad that people struggling to keep warm in damp homes feel they need to use them. They don't, they're far better off with an oil filled rad or a fan heater, which is cheaper to buy, too.
I'd say the ideal is to use thermostatically controlled oil filled rads to keep the temperature up generally, with fan heaters in work areas. I'm less than keen on leaving fan heaters unattended, due to the risk of the fan becoming bored with going round, while the heating element continues to do its thing, but oil filled rads are about as safe as a portable heater can be, really.
Yes, energy advice was my profession...