Good question, look at your bills and you will see the cost in p/kwh for off peak electricity and for your gas. Gas is always a lot cheaper than electricity but is not quite so efficient at heating water. With an immersion heater all the heat goes in the water, but a gas boiler has only a certain conversion efficiency. Gas is normally about 4p/kwh so unless the elctricity is in the range of about 6p I would stick to gas.
@Mary How long is a piece of string? You have to take into account how low/high you set your CH. whether you have all your doors open/closed. Thermostatic valves on radiators? How long your timers are set to be on? How draughty is your home? Do you have a cylinder for domestic hot water etc.
Also, are you out at work all day, do you get up early/stay up late? is your boiler (if it is a gas boiler) efficient, a combi, old, new, reliable... The list is endless. There's also some debate over whether one or other is better, as consistent heating can reduce condensation but shorten the life of modern boilers.
I suggest you try both ways for a week or two, reading your meters before/during and after. Do the maths and make a decision based on what you actually find works for your home.
A friend who has worked for an energy company has told me I am spending too much on gas I have a gas boiler She advised me to turn the water off when i am not using it I assumed though that Scottish Power take the daily rate
Does anyone know if this is correct or should i wait to see how much i am saving i have never ever turned the water off on the boiler but after a while i have got used to it Does anyone have an opinion Thank you