Drivers in North Yorkshire describe their Christmas getaways
The Christmas getaway has passed off "generally smoothly" for motorists as weather improved across much of the UK.
The Highways Agency says major roads in England are ice-free but unsalted roads are still dangerous. Despite snow, main routes in Scotland have remained open.
Most airports have stayed open, albeit with delays, while Eurostar has been running a two-thirds service.
Heavy snow is forecast for northern and eastern Scotland, while central eastern England could also see some sleet.
BBC weather forecaster Nick Miller said the Met Office had issued warnings about ice in many areas.
"It's looking pretty tricky as we go through the night into Christmas morning," he said.
Drivers were facing foggy conditions in areas including Wiltshire and across the Pennines.
Breakdown organisations had predicted up to 6m people could take to the roads on Christmas Eve and at one stage the AA was dealing with about 1,400 breakdowns per hour.
The Highways Agency has lifted roadworks at 44 sites until 3 January and a spokeswoman said Christmas Eve had been quieter than Wednesday.
"The roads have been busy but generally it has gone quite smoothly," she said, adding that traffic volumes dipped from about 1600 GMT.
There were reports of congestion on motorways in south-eastern England but no major problems.
Icy conditions caused crashes around the country on Wednesday night
The AA's head of road safety Andrew Howard said it was possible people were waiting until Christmas morning to travel.
He warned that even roads where ice had thawed could be dangerous.
"The trouble is that the salt gets washed away. If it refreezes then you don't have salt on the roads and there's very little you can do about it," he said.
"Even if a road has been salted, it doesn't mean it's safe."
On Wednesday night in Lincolnshire one person was reported killed as black ice caused some 40 crashes, police said.
RAC patrol manager David Hoares added: "You really must check your local weather and the traffic situation where you live and where your journey is going to before you decide whether you have to travel."
Eurostar was running about a two-thirds service on Christmas Eve, after suspending services on Saturday, Sunday and Monday following train breakdowns.
The company said any passengers with tickets for 19-24 December would be able to travel.
A Eurostar spokeswoman said it was on course to get everyone away for Christmas on Thursday.
Meanwhile the Anglo-French supervisory body has criticised the set-up of Eurostar and Eurotunnel for failing to "meet the information needs of passengers".
Both firms have acknowledged the comments of the Channel Tunnel Intergovernmental Commission, raised after an extraordinary meeting.
Some 300,000 people were travelling through the UK's airports on Christmas Eve.
There have been delays at most airports, including Manchester, Glasgow, Edinburgh and Prestwick where staff have had to clear snow and ice from runways.
EasyJet had to cancel more than 20 Thursday flights, while British Airways said the majority of its flights were operating normally but warned passengers to check before setting off for the airport.
Gatwick said it was operating normally but warned of minor delays.
Passengers queued outside St Pancras Station as services returned to normal
British Airways said its services were running normally at Heathrow, with the airport expected to handle around 144,000 passengers on Thursday.
However, passengers on a London to Belfast Aer Lingus flight that should have left Heathrow at 1500 GMT on Wednesday were still waiting to get away at noon on Christmas Eve.
There are some delays and cancellations at Stansted airport in Essex, where 34,000 people are passing through.
On Wednesday a Ryanair jet with 129 people on board skidded off the runway at Prestwick after hitting a patch of ice. No-one was hurt.
On the trains, Scotrail says services are restricted between Glasgow Central station and Ayr, Largs, Ardrossan, Gourock and Wemyss Bay.
The weather has wreaked havoc with the sporting calendar.
The National Hunt Boxing Day meeting at Towcester has already been called off, with meetings at Sedgefield, Wetherby, Market Rasen and Huntingdon facing late inspections.
Meanwhile, all but two of the Scottish Football League's Saturday fixtures have been postponed.
Prospects of a white Christmas have receded for most of the UK.
However, parts of Northern Ireland, the lowlands and southern uplands of Scotland and the far north of England could see light snow showers on Friday.
It will be a very cold night across those areas, with temperatures as low as minus 7C in the Highlands.
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