I imagine that Oct in Norway is like December in the UK (only prettier).
In cold damp conditions it is vital to stay as dry as you can, from rain, sweat or condensation especially if you face a big descent. I may change a wet inner layer at the top of a big hill to a nice dry one on very cold, damp days. I use a windproof rather than a waterproof unless rain is falling. A lot of this is standard winter cycling lore so have a good read of icebike.
Feet can be particularly exposed so avoid tight footwear, use layers of woolen socks. If you dont have waterproof shoes or boots, try some "Sealskin" wproof socks or in extremis use plastic bags between socks.
Falling on ice is a skill which takes practice. In my experience you cant fight black ice, you cant brake or steer or accelerate. If you do find your bike slipping away, tuck in and roll to spread the impact.