My feet were constantly freezing even in socks and slippers to the point where they were actually painful.
These are really warm toasty socks, VERY thick though so you probably wouldn't be able to wear them with your normal shoes but perfect for wellies or around the house.
There is no heel in them, they are more tube like so size isn't a massive deal. I bought a size 5.5 for my son but he couldn't wear them with his shoes so I wear them instead! (I'm a size 7). I Can totally recommend I have not had one "cold feet day" while wearing these socks - Totally recommend.