it will help a lot.
we live in NZ, where houses are uninsulated and we have single pane glass from the early 1900s. there also isn't any central heat. the thermal curtains are a necessity.
our winters are not that cold (about 40-45 degrees F, sometimes dipping toward freezing at night on occasion, btu that's rare) but they are damp. damp is the biggest issue, because the cold stays with you.
here is what we did:
1. always dress in layers: wool or silk under layer, t-shirt/jeans layer (or flannel PJs), and then sweater/fleece layer. this is indoors, mind you. sometimes, fingerless gloves, definitely socks. if you get warm, then you can always take off a layer.
2. curtains, good thermal insulating curtains, are a necessity. if i were to have my own made, i would likely have them made out of good old heavy wool. and, seriously think--like wool felt or kilt fabric sorts of wool. no messing around, straight up, wool. it's the bomb, wool. i love it. wool wool wool wool wool!
3. bedding-- our bedding makes a HUGE difference. we have a wool fleece mattress cover. cushy, cool when it's hot outside, hot when it's cold outside. i don't know how it does it. we then have cotton sheets for breath-ability. then, "winter weight" bedding (yu can purchase winter weight and summer weight blankets here). then two wool blankets that go on top of that.
4. 'hotties'--the ubiquitous hot water bottle. everywhere you go, people have them here. they love them. people knit special sweaters for them (out of wool) and everything. seriously. fill them with boiling water, pop them into your bed before you get in, pull them out before you get into bed, and voila, nice toasty bed to get into. a lot of people also spend a lot of time cuddled up with them.
5. lots of throw blankets around--preferably wool--so that where ever you are around the house, you can have a warm blanket to get under.
6. heat where you are-- because we don't usually have central air/heat here, a lot of people either have wood burning stoves or heat pumps. if you aren't lucky enough to have those (and msot people aren't) then you rely on space heaters. there are many varieties available, but the best both heat and dehumidify, because dry is necessary. we are lucky enough to have a heat pump, which we put on a timer to heat jsut before we would rise, and then in the evenings after dinner. this helped keep our bedding and clothes dry, so we were less cold.
an efficient space heater can cut costs, and if you get one that is mobile, you're not heating rooms that you are not in. we did not heat overnight, as the wool and our PJs kept us warm. it worked out really well.
sometimes, if it was very cold at night, we'd refill the hotties and toss them back into bed with us, but otherwise we did quite well.
but, since you're mostly thinking about curtains--heavy wool curtains, perhaps even with a thermal insulation--will help a LOT.
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