your link doesn't mention whether gas/electricity are used for heating (including hot water), plus UK houses are infamous for having horrible insulation
and I am working from home with big external display (so does my wife) as well for many years, TV is running roughly 5 hours per day, game console around <1hr and that 1.2MWh includes also AC set to 26C when it will get hot, though not spending that much time at home during July/August
240kWh per month, 35cent per kWh and a base price of 10 Euros.