Layer up. I'm in Dundee and temps have been all over the shop the last month or so (start -1c some days, 11c the next...).
Standard winter kit for me at the minute from top to bottom:
Noggin
Cycling cap (generic DHB one, nothing)
Neck
Buff (generic one from Amazon)
Body
Long sleeve base layer (Aldi special buy from approximately 12 years ago, fraying but does the job)
Long sleeve top (bought a couple of winter ones from Vogue Cycling. Not too heavy, not too light, keeps you cosy)
If it's really cold i'll put my Aldi special buy winter jacket on, but that's only if it's snowing out!
Digits
SealSkinz Gauntlets (arguably overkill but i'd rather have warm fingers than cold ones)
If it happens to be a little warmer then it's Defeet Dura gloves - nothing fancy.
On ma belly and hocks
Bib longs (FDX jobbies from Amazon for interest)
Over ma belly and hocks
A pair of XL cycling trousers on top (Aldi special buy that was/is too big but goes well over other stuff)
Tootsies
Defeet Woolie Boolies (not essential, but not bad either)
Generic Shimano Shoes (like, not winter boots or anything)
Neoprene overshoes (Aldi special buy from a few seasons ago)
I am not a skinny whippet either (coming in at about 94-96kg these days) so the winter padding helps.