I always wear an under shirt or cami tank under my long sleeved wool tops and then a coat when ever I go out on freezing days. I can't stand the wind so I also wear some sort of hat and scarf if it's super cold out to keep my head warm.
I second this suggestion. Even just wearing a cami under a t-shirt was enough warmth for me on many days. Primark has some for £2 that have a shelf bra built in, but I always wore a bra under it as well. I also picked up a 2-pack that didn't have a shelf bra at Debenham's for £8. The important thing is to make sure the cami is long enough. If you can tuck it into your trousers, then you don't have to worry about a chill on your lower back if your pants slide down.
If I was just at Tim's house during the day, I'd wear sweatpants or fleece lounge pants to stay warm and only wore jeans and cords when I left the house.
Also - it's surprising how warm a pair of tights can be, either worn with a skirt or even worn under jeans.
When we were out and about I always made sure I had a bag with me (tote or a backpack) to discard my layers into if I took things off.
As far as hats go - Tim bought me a fleece lined woolen hat in Hay-on-Wye that had ear flaps. If it was particularly windy, I'd tie it in place under my chin. Looked silly, but I stayed warm! I also discovered just how much I love flip-top mittens last winter.
ETA - and underwear matters. plain cotton panties will keep you warmer than silk or synthetic. I really liked the boy short style as it guaranteed butt coverage!