I can recomend marks and sparks ladies ultra warm . I'm wearing a pair today, and they are realy warm, and soft, wash and dry very quickly.
Only £16 when I bought mine a couple of years ago. Don't know present prices, but they are definatly worth every penny. Warmer and cheaper than the ones I bought for Sweden for use in -20°
I could only get size 16, I'm a size 12/14, but I find that they fit fine, and are more comfy than my real size, so I'd say go a size bigger than your normal dress size for a comfy relaxed fit. They will still keep you cosy.