Some good ideas so far. Out the other night around Filey (Yorkshire coast) I was warm enough and it was well below zero.
For my feet, sock liners from
Go Outdoors inside woollen/woollen blend socks and good boots (I had
Angler's Socks from Arco and
Snowbee Rockhoppers from Veals but there are plenty of makes of each to choose from) worked well. Go Outdoors are doing a two-for-the-price-of-one on sock liners and socks including long thermals at the moment. If you're getting out of the car a few yards from your mark thermal socks may do the job but they're likely to get sweat soaked then very cold if you walk or climb any distance in them. The same thing applies for boots. Static rubber will give you good insulation. If you're moving you need something which will wick away any sweat which renders pure rubber useless.
Lots more to choose from and decide between for hands. I managed the other night but got cold hands for short spells and had to warm up. Ideas like rubbing petroleum jelly into the skin with just thin rubber gloves to keep the wind off are OK for a mild chill but thy can't cope with a sharp frost. So I've just put
fisherman's gloves on my shopping list. You can poke your thumb and two fingers through when needed. I don't think the fingerless type will help much. But my fully covering very warm Goretex outdoor gloves won't help 'cos I'll need to take them off altogether to bait a hook or tie a knot.
To complete the picture, I've been using
"bandits" from Go Outdoors in conjunction with beanie hats, all tucked under my parka hood for my head, neck and face. But I think a good balaclava would probably do as good a job with less messing about. So that's also on my shopping list.