Yes, this is exactly what I do. My conservatory was re-purposed as a dining room, so I do need to use it. However, the central heating struggles to heat it even to 15 degrees in this weather and the problem is compounded by the fact that the radiator is about half the size it should be, so the gas bill literally goes through the roof if I attempt to heat the conservatory using mains gas.
I use
this heater. It heats the entire space in about 15 minutes. Extremely effective and I use it only for about an hour a day when I want to eat dinner. It's pricier than a standard oil-filled radiator, but it heats up almost instantly and according to the literature is substantially more efficient than a oil-filled radiator.