Apart from leaving my PC on (its 10 years old and doesn't like being turn on and off) I really cant see where we can shave any usage potentially apart from using the washer and dryer a bit less. All of our household lighting is now LED. There are 5 of us in this house. I suppose swapping out the electric shower would help as we could run that off the boiler. I really don't see where we can save a lot but I suppose there is a decent incentive if its going to double fairly soon.
Id check how much loft insulation you have before anything else. You should be looking at at least 300mm of normal rock wool by modern standards, many suggest 450+. It’s really very cheap too.
It’s often the small things which add up to a lot of money, eg. Running the thermostat AND TRVs at 18 and getting people to wear jumpers. Asking people not to take 20 mins in the shower rather than the 5-6 you actually need (particularly on electric), make sure the washing machine is actually full and running it only on the most eco setting (these tend to be longer but use way less water and electric), drying clothing outside, even in winter, if it isn’t raining it will still dry etc etc.