Think about all things that need heat.
Quick showers (I have it down to 3 minutes)
Make sure washing machine is full, avoid tumble dryer, wash according to weather
Save all dish washing for one daily wash, rinse in cold water
When the heating is off don't let yourself get cold as its harder to warm up than keep warm iyswim (warm layers and moving around helps)
I have a heat pad that I plug in when I am sitting still (costs pennies to run and stops the cold from setting in). You could also use a hot water bottle but will need topping up with hot water
Only fill the kettle with exactly what you need
Avoid using oven, but if you do make sure there are a few things in there for bulk cooking then let the heat out to warm up the room
Turn hob right down as soon as things have heated up, use pans with lids
Use rooms where you get the most sun
A plumber told me central heating a whole house is cheaper than one gas/electric fire
Blankets and dressing gowns
As soon as the heating goes off retire to bed to watch tv/computer (better if your bedroom is upstairs because the heat will rise and take longer to cool)
I know it all sounds grim but daily changes to habits do add up. Good luck x