Indeed temperatures are going to fall to below freezing quite widely across the country tonight but I think humidity levels may be somewhat reduced so the fog and hoar frost risk won't be as extensive as last night.
Tonight should be the last night for that kind of thing for a while before the Atlantic stuff come steaming in during the course of tomorrow with increasing cloud cover and then eventually the rain and stong winds turning up to affect most places on Friday.
Then all back to normal with westerly type winds bringing sunny spells and showers to all parts over the weekend.