When it gets cold enough that one can feel it, I wear a down jacket next to my down comforter and polyester blanket set. Any colder and I put my sleep bag underneath the blankets to keep my feet warm and put down my jacket hood. If its really cold, a balaclava keeps the face warm.
I’ve learned to do without heating since my landlord won’t pay for it.
You sound like you are in a real situation, how much is a kilowatt of electricity for you?