Go round the house now and identify where the draughts are and get them filled - I was amazed at the difference this made. You can get rolls of the sticky draught excluder at DIY shops and on-line. A tiny gap will let so much cold in (and heat out). Not just external doors either - try and prevent internal draughts and get used to closing doors to keep heat in/cold out.
Get some cheap fleece blankets to hang at windows - we have a huge, decorative glass window and did this last year. Stretched it across and used heavy duty ‘stick n stick’ Velcro to secure it. Again, it made a massive difference and prevented heat escaping. I think it works by creating a cold pocket of air between the window and the room itself - the opposite worked in the summer, the hot air was trapped between the blanket and window.
You can buy thermal curtain liners, but I found fleece worked just as well and was far cheaper and the blankets are cheap-cheap in places like Home Bargains, B&M and Amazon.
I also shut off rooms I knew I wasn’t going to use. Had the window vents open in these rooms so they’d air and then sealed off the door to prevent heat escaping.
Then it’s a case of heating yourself and the room you’re in - heated throws, gilets, thermals etc, opening the oven door after cooking can heat a kitchen if there’s no draughts.
I empathise - it’s so shit. However, I will say we got used to it. It takes a few weeks to adjust though and my mind never really adjusted, I was fairly warm physically but still pissed off at the situation, having taken being warm in winter for granted.