It’s the same thing. Say you have a bill of 120€/year. On average that comes to 10€/month (120€ divided by 12 months). If you have save 10% a month you save 1€, which after 12 months becomes a saving of 12€. Now do that yearly: 10% of 120€ is… 12€.
are you running bitcoin farm or cook and heat with electricity with 100 eur monthly bill? my yearly consumption for whole household of 4 people is around 1.2MWh (gas cooking, and external grid central heating), which makes like <400EUR per year in Czechia (infamous for high electricity prices across Europe) and already now most of my fees are not really my consumption, but distribution and other stuff, it's even worse with my gas cooking with only 0.5MWh per year, where I paid almost only fixed fees and not the actual consumption, but tried cooking on induction and hated it
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
Those figures will include heating from either source, yes. Non-heating electricity consumption tends to be a tiny fraction of energy use. Centralized "district heating" is pretty rare in the UK.