Weather warnings remain in place as wintry conditions threaten to continue into the morning rush hour.
It comes as temperatures dipped below freezing yet again overnight across many northern areas, bringing potential disruption on roads and untreated surfaces.
Wales, the north-east of England, the far north of Scotland and Northern Ireland have all been issued a yellow weather warning for ice until 10am by the Met Office.
Drivers in affected areas have been advised to "plan ahead" for their journey, listen to weather forecasts and adjust their driving behaviour if cold weather hazards are present.
Dale Hipkiss, National Network Manager at National Highways, added that motorists should also "allow lots of extra time" when travelling in case they encounter delays.
A Level 3 Cold Weather Alert issued by the UK Health Security Agency (UKHSA) is also in force for all of England until 9am.
The government advisory - which was extended until Friday after being applied earlier this week - is accompanied by a message asking people to check in on "family, friends and relatives who may be more vulnerable to the cold weather".
Night-time conditions are likely to remain cold into the weekend, especially in southern areas, with lows of -1C expected in the capital according to the latest Met Office forecast.
Some freezing fog is also possible in England and Wales.
Milder conditions are expected to arrive early next week, with temperatures nudging towards the mid-single figures overnight by Tuesday and Wednesday.
UK weather forecast:
Cold with overnight ice and freezing fog in places.
This Evening and Tonight:
Showers, still wintry at times, becoming confined to northern and eastern areas. Elsewhere, dry with long clear spells. Very cold with a hard frost for many.
Friday:
Wintry showers for the north, these becoming confined to North Sea coasts with time. Otherwise, fine and cold, though with isolated freezing fog patches which may be slow to clear.
Outlook for Saturday to Monday:
Outbreaks of rain in the northwest, edging south and east through the weekend into early next week, introducing milder conditions. Some freezing fog for England and Wales at the weekend.
