You can sign up for emails from The Highway Code and they share different rules, this is the latest one I have had.
The Highway Code applies to England, Scotland and Wales and is essential reading for everyone.
Before entering fog check your mirrors then slow down. If the word ‘Fog’ is shown on a roadside signal but the road is clear, be prepared for a bank of fog or drifting patchy fog ahead. Even if it seems to be clearing, you can suddenly find yourself in thick fog.