as I said it's excluding external central heating which covers also hot water for shower, so it always comes down what you use for heating to compare, someone use gas, someone electricity and someone is outsourcing it to heating factory (my case) on different bill
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
