Eels:
I can't work out exactly how much electricity you're using because tariffs vary but �40 to �50 per month equates to about �135 per quarter.
On the Eastern Gas direct debit tariff, for my part of the country (East Anglia) this equates to using about 14 kilowatt hours per day. That's a lot.
Your fridge and/or freezer probably use about 2 kWh each day.
Your lighting requirements probably don't use more than 1 kWh per day.
If you leave your TV in standby mode, rather than turning it off, it's probably costing you at least �30 per year but it's total power consumption (even if you watch lots of TV) is probably still no more than 2kWh per day.
Your laundry requirements (washing & drying) probably average out at around 2kWh per day.
You can probably throw in a maximum of 2 kWh more to cover average use of your computer, scanner, printer, DVD player, radios, hi-fi, etc.
So we've got a grand total of 9kWh hours per day. But you're paying for 14kWh per day. So where's the rest come from?
Well, if your immersion heater is actually running for just 1 hour 40 minutes per day, it will use, surprise, surprise, 5kW hours per day. (i.e. over a third of your total electricity usage)
Now are you going to turn it off?
Chris