If you're active you really don't need more than you need here.
Bonus if it's not raining!
I went on a very active but very cold trip to Norway in Feb. (-5c to 0c excluding wind)
And then a active trip to Greenland in August (0c ish).
For the greenland trip had to pack light as was kayaking and camping for 5 nights.
All I needed was
Bottom
Acai Polar leggings (dual layered leggings, but nothing underneath them)
My Gtx HOKA trail. Code boots
Some good thermal merino socks (important)
On top
A merino base layer
Arc'teryx Proton midlayer (one of my favourites pieces of kit)
Thick winter gloves (important)
Buff (I think it's called for neck)
Warm hat. Mine was a cheap thing off ebay.
For when I was still I also had my
Mountain equipment down jacket.
And if it rained Gtx waterproof jacket and over trousers
I can't stress how amazing merino is. It takes ages to smell. Can't believe how. Good it is.
Really. You just need what you need for a cold UK winter. If it's sunny and dry and cold you won't need much.
Look for wind breaker type clothes.
Caveat... I run warm. I wore the least on the trip of anyone. So what I've listed is probably a minimum.
Activity level is really important. If you're sitting still you'll need good thermals.
Here's a pic of me in Greenland on a glacier with my kit.
The guide was adamant I needed more layers, so I wore my down jacket. But I overheated, badly.