Keep the central heating off and even when needed don't push it above 19.
Wear layers.
Turn everything off when not in use.
Turn the water temperature down a little on the boiler, you won't notice that 2-3 degree drop, but it does save.
I have no electrical appliances in my kitchen, I have a double gas stove and hob, a job top kettle, I grill bread under the grill for toast. Gas is cheaper pkwh than electricity.
I also light candles in the evenings in the lounge whilst watching tv. Very rarely have the big lights on just lamps in the bedrooms with led bulbs.
The only "big light" that gets used is the bathroom and the kitchen and they have energy efficient bulbs in them.
Curtains on external doors, draught excluders on the floor of the living room and bedrooms. Socks and slippers worn in the house.
I'm in pay as you go smart so I can see the credit being used up and usage hourly really.