"Can any of you with pre pay meters change? They sound like they use an extortionate amount!"
I agree. I have just checked our monthly bill. We pay about £3.50 a day for gas and electricity to heat radiators and water and power all of our electrical items for a 4 bedroom house. I only work two days a week and OH works from home and we don't hesitate to put the heating on in these kind of temperatures.
Can I suggest that those of you who rely on electricity for heating to get a convector heater. They are far cheaper to run than fan heaters, more efficient at heating a room and are thermostatically controlled.