Be very careful of Octopus.
Their night rate may be cheap but their daily rate is expensive. When I did the maths the day rate was 30% more expensive than I currently pay. It wouldn’t be cheaper for me to be on Octopus.
Someone pointed me towards OVO as their day rate is similar to what I’m currently on.
There isn’t a simple answer as you need to do the maths yourself. There are a lot of factors such as can you move any of your usage such as washing machine and dishwasher use.