>>1135273For the windbreaker, you need 2 jackets. One should be like pic related, polyester & lycra, very thin, a bit stretchy, and windproof. It's a softshell, but most softshells are too substantial and don't breathe well. Brightly coloured is best for safety. Thin.
The other should be a light shell jacket that is waterproof. Light and compact enough to carry and not be a burden. It shouldn't have any insulation, get that in your mid layer.
If you wear a waterproof jacket or pants, you'll sweat, they won't whick, and that's not good. The sweat will make you cold. Only wear waterproof clothing when it's raining. You need the windproof though, so that's the first jacket. They layer together well.
Thermal leggings (polyester) & shorts. You can go rain overpants in the rain, just get wet, or wear some running/ cycling winter lycra tights, which are good when they're wet.
Tight thermal baselayer (polyester or merino), and a looser thermal baselayer (poly or merino).
Add a midlayer if that's not enough, a down jacket, merino mid, or a fleece. A thin merino mid is the best if you can get away with it, down jacket the warmest, fleece is cheapest.
Expensive merino socks are definitely worth it. Personally I don't like really thick socks, you can get a lot of warmth from quite thin good ones.
TLDR; get light thin layers that breathe, and ride the fine line of just enough clothing to cycle comfortably in the cold.