It’s more economical and efficient to have your heating on low to keep your house slightly warm all the time than it is to switch it off then crank it up for an hour or so. Have blankets in your living room and put them on your lap when you sit down. The BBC advice to only heat the room you are in is inefficient and will lead to damp in the unheated rooms.
Even if your windows are double glazed they will still benefit from adding a layer of extra insulation from the plastic skrinking stuff. You can add it to each panel, so you can still open them to air out the room. I’m pretty sure Aldi are selling it at the moment. If you put it on carefully it’s barely visible, but it will reduce condensation and the chilly waft from the glass.
Lots of other ideas; if you’ve cooked something in the oven, leave the oven door open a bit to let the heat out once you’re done. Curtain over/just inside the front door, rugs and slippers if your floors are cold, and my personal favourite, a large dog on your lap!
Whilst to most of us it may seem obvious to ‘put a jumper on’ it’s amazing how many people don’t, I know several people (men…..) who complain they are cold, but are pottering around the house in November, barefoot and in shorts & t-shirts.