The best way to heat a small flat is to run a butane fire. The main gas supplier company on the UK is Calor and they supply small 15 killogram gas tanks. Butane gas is like propane but it boils at a higher temperature so it is no good for outside because it could become too cold for the gas to come out of the tank but it is safer than propane inside because it puts less pressure on the walls of the tank at room temperature.
In this decade I went though a phase where I liked to eat spicy cheese, I would get home in the winter after work feeling very tired and would turn on the Butane gas fire. I would press a lever and press the ignition button and it would make a banging sound then the gas would ignite and if the gas tank was fresh the gass would come out slowly and spluter slightly. Then I would make some nice spicy cheese sandwiches, then I would turn on the TV and watch true crime mystery shows like FBI files on netflix and I would stare at the Butane gas fire while I eat my spicy cheese sandwiches. The ceramic grill would glow bright red and there would be dark smears where it wasn't quite uniform with the rest of the grill. Sometimes I would put my feet near the fire and that was bliss. Then I would curl up on the couch like a little cat and be grateful I have a home to go to. I will always remember these times and look back with happy thoughts.