We have a thermostat on the heating system, so the gas boiler only turns on when the temp drops below the pre-set value. And we have it at different temps for different parts of the day (I think it's 12 degrees overnight, set to come up to 20 in the early morning just before we get up, then stay above 18 on the days we WFH/weekends or 12 on other days we won't be there so it's not too cold to reheat, back up to 19/20 for the evening when we will be sitting around and also needing hot water). We can override it if we want to boost for extra heat.
We got PV solar panels last winter which have made a huge difference! We're running almost everything in the house on solar power during the day except on rainy days, and once the house no longer needs power, it is diverted into the hot tank first and only exported to the grid when the hot tank hits the max temp. So we are running the washing machine and dishwasher on eco settings and timers so they are running at different times (trying to maximise our use of our own power). And I will often recharge powerbanks during the day and use those to recharge devices/phones in the evenings.
We tend to hang the laundry out if there is any good drying outdoors, and often leave it on the clothes horse in the kitchen/diner overnight if not. I would love a laundry maid but it won't work in the room - DMIL has one in her kitchen and gets great drying from the wood stove in that room (rural house, not great heating, lots of windfall trees for timber). We also only run the appliances when they are full.
Insulation to keep any heat you generate in the house is really important. Ours was not done all at once (we're in the house 20 years next week) but we have put in double glazing (all windows were single glazed), thick insulation on back external walls when we extended and also attic when we extended up there, into the empty roof space over the "bay" window in the north-facing sitting room (OMG that was a HUGE improvement to that room!), and better front and back doors for insulation and blocking draughts in all sorts of places. The vents that were in all the bedrooms upstairs were basically just open holes letting heat pour out - so we got proper covers that can be closed and filled in the gaps around them when we fitted them, and also sealed up holes we found in the bathroom floor when we replaced the bath.
We had been using a chimney balloon to block the chimney when we weren't using the open fire, as it let lots of draughts in. And the actual fire was so inefficient when it was lit. But we actually replaced it with an enclosed stove about 5 years ago - so now a much smaller fire lets much more heat into the room (and burns more cleanly and completely - there is a LOT less ash and almost no cinders left), and keeping the door and vents closed at other times has really reduced the cold air leaking back in. In previous years before we fixed windows and insulation, I had very thick curtains with blackout lining and also interlined (like a thin blanket between the fabric and lining) in that room, and also good lined curtains in other rooms, to help keep the heat in the room. Closing the curtains as soon as it got dark made a big difference to keeping heat in - even if we weren't using that room. And also closing the doors of any rooms that you are not using - keep the heat in the rooms you are using.
I have been using a fleece blanket over my knees when WFH in cooler days, rather than turning on the heating, and often a thick cardigan (that looks ok on camera) on top if needed. And we have always been people to wear proper clothes - so putting on a vest/thermals on colder days, wearing thick fluffy socks if not doing a lot of moving around, etc. I like the idea of an electric blanket for that purpose! I also use hot water bottles in bed, and occasionally when WFH. And we use a lot of throws over us when curled up on the couch in the evenings.
I love the idea of the airfryer for the taco shells. We use ours a fair bit. But we also do use the oven as I will have 3/4 different things in there at once - all the bits for dinner, baking bread or cakes, roasting squashes to use for soup the next day....etc. I sometimes also use the oven to make dinner on the timer so it's ready when we get it (which in itself helps as reduces the load on grid at absolute peak as it's often slow cooked stews that need the energy to heat the oven earlier and only need minimal energy to finish cooking in the evening peak). I also use a slow-cooker at times which also uses a lot less energy. (Also, once everything is cooked and I've turned off the oven, if there is no danger of small DCs running around, I will often leave the door open and let the heat out into the room for a couple of minutes - the opposite to shutting the door quickly on both the oven and the fridge/freezer to keep the heat/cold in when they are in use).
A lot of those things cost us money - but we have done them over the whole time we've been here. Insulation, better windows and doors, stove, solar, better gas boiler - all were expensive but worth it over time for the improvements they gave and reduced costs of running the house.
But not everything is hugely expensive. When we first moved in, the curtains cost a lot but even adding in the cost of the sewing machine I bought - I had saved a LOAD by making them myself compared to getting them made (and you couldn't get interlined, or even blackout lined off the shelf) - and the machine has made a load more things and done a lot of repairs since then. Most of our fleeces came from Ikea and Primark type places. And some things, like finding and plugging gaps, can be done with things like bubble wrap leftover from packaging, or cheap rolls of puffy tape from DIY stores to put around windows and doors. And just remembering to close curtains and internal doors is surprisingly effective on particularly cold days.