I know prices are different from the us to uk, but a 50 watt on 12 hours a day should only be like 5$ a month. Heating pads have a low wattage, so also like 5$ a month. 1,000kw is about 100$ so ----- 50 watts x 12 hours= 600 watts, there's a 1000 watts in one kw. So 50 cents a day MAX. but it gives u an idea how to figure that out with anything and it's wattage