Anyway, what you need is:
Merino base layers / thermals. Top and bottom.
Merino socks. Decent ones, can get special thick ones from the likes of Smartwool for this kinda thing.
Look at your footwear. Yes it has to be smart, but could you wear a smart thermally lined boot or similar?
Could you wear a down jacket or gilet?
Today I wore: Merino baselayer, t shirt, sweater, thick fleece, (thin) snowboarding jacket and my hi viz goretex shell, with merino long johns and thick jeans, and merino socks x2 under Dunlop rig-air thermally lined boots.