It's not AIBU but all the threads seem to be in here so thought it was worth adding because there are so many and I've spent an hour explaining it to people yesterday in RL
If you are looking at fixing check here
https://www.moneysavingexpert.com/utilities/-are-there-any-cheap--fixed-energy-deals-currently-worth-it--/
This is useful
https://www.moneysavingexpert.com/utilities/what-are-the-price-cap-unit-rates-/
fixed rate fixes your KWH AND STANDING CHARGE. Not your payment per month
So it's no good saying it'll be £500 per month, it depends what you use! You need to look at the kWh and standing charge and how much you use
Imagine your energy is petrol, you're fixing the price per litre but how much you put in is controlled by you. Fixing means you fill up with a set cost for energy rather than the variable rate
So you pay £1 per kWh (random number) rather than going to the garage and it might be 80p or it could be £1.50. It doesn't help with how much you fill up, but it means you know exactly how much each kWh is costing
I'm the least adult adult but energy costs is one thing that I can usually explain!