Selfsufficientish.com

Is electricity cheaper at night time?
If it is what time does it beciome cheaper and at what time does it become more expensive?

Only if you have a twin tarrif meter.

My experience of these (a long time ago, when I lived somewhere with night storage heaters) is that you will pay slightly more for the daytime tarrif, and get the night time stuff cheaper.

A twin tarrif meter will have a timer on it so it measures your consumption at two different rates, depending upon the time of day. You would know about it if you had one of these (you bill would specify it)

we had a twin tarrif meter in our old house as we had electric storage heaters. think it was called economy 7. dont know what the price difference is though, just that it was cheaper at night while the heaters charged up

We have this too, which is why I like to run my dishwasher, tumble dryer and washing machine overnight if possible. I have no clue what the price difference is though. I spose I ought to check ....

I used to work for Eastern/TXU/Powergen. I doubt things have changed that much...
Most home meters collate both the day & night reads. Power is cheaper at night because the demand is lower. What matters however, is how it's retailed. An Economy 7 tariff, offers a discounted night rate against a higher day rate. The typical night being a particularly "useful" midnight until seven. This means, unless you have storage heaters, run the dishwasher, washing machine, watch the TV and so on, at that time, there is a fair chance you will pay more.

I would get some quotes from the various suppliers, the night rate can cover different times (BST/GMT too). Consider what a Single Rate tariff would cost you, being mindful of the standing charge.
Power is traded and settled on a half-hourly basis, people pay a premium to have it simplified (although the bills are not simple). I would hope in the future, cheaper forms of HH metering will become available. Enabling people to better manage their usage and save money for doing so.