Fog is quite common at this time of year, so here’s some advice about how to drive in these conditions;
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.
You MUST NOT use front or rear fog lights unless visibility is seriously reduced (see Highways Code Rule 226) as they dazzle other road users and can obscure your brake lights. You MUST switch them off when visibility improves (Law RVLR regs 25 & 27).