Image source, Getty Images

The president of breakdown provider the AA has compared driving on many "atrocious" UK roads to skating on ice rinks.

Edmund King said those debating whether or not to risk the roads, should "bear in mind that being able to reach your destination this morning doesn't necessarily mean you will be able to get home again later".

By 08:30 GMT on Thursday morning the AA said it had already answered calls from more than 100 drivers stuck in snow, with East Anglia and the North East the worst-hit regions.

National Grid has warned it may not have enough gas to meet UK demand today, and has asked suppliers to provide more.

In the event that there is still a deficit, large gas users such as industry and large businesses will be asked to use less gas.

Demand for gas on Wednesday hit a six-year high as cold weather swept the UK.

The Met Office's red weather warning for south Wales and parts of south-west England is for 15:00 GMT on Thursday until 14:00 GMT on Friday.

But how bad will the weather actually be?

The Met Office's chief forecaster says: "Widespread snow is expected to develop through Thursday afternoon and evening.

"Around 10 to 20cm is likely to fall widely, with the potential for up to 30 to 50cm over parts of Dartmoor, Exmoor and parts of south-east Wales.

"Snowfall will be accompanied by strong to gale easterly winds, leading to severe drifting of lying snow especially in upland areas.

"Severe cold and wind chill will compound the dangerous conditions, with very poor visibility.

"Towards midnight, there is a chance of snow turning to freezing rain in places, mainly across the south of the area, with widespread icy stretches making driving conditions particularly dangerous."

Image source, Getty Images

Image source, Pa

• Arriva Trains Wales running amended timetables throughout Wales and has cancelled all trains from Cardiff to Manchester until at least 12:00 GMT
• Paddington station has closed - Great Western Railway trains will start and terminate at Reading instead
• There is currently no Heathrow Express service between London Paddington and Heathrow Airport
• East Midlands Trains are unable to run any of their trains in both directions between Nottingham and Skegness
• There are numerous delays and cancellations on the Northern network with all trains through Huddersfield are delayed by up to 50 minutes or cancelled
• Scot Rail is only running services from Aberdeen to Inverness and Dundee, and from Inverness to Perth and Kyle of Lochalsh and Wick
• Virgin Trains is not running any trains between Carlisle and Scotland and there are no replacement buses
• CrossCountry services are currently suspended between Edinburgh and Glasgow Central / Newcastle until at least 10:00 GMT
• Tfl Rail are reporting minor delays throughout its network
• Great Northern, Merseyrail and Chiltern Railways say they are running a full service

The Met Office has updated its weather warnings for various parts of the UK.

There are now red weather warnings for: Central Scotland, Lothian and Borders, Strathclyde, south-west England and south Wales.

There are now amber weather warnings for: The east coast of Scotland, central Scotland, the north east of England, central and southern Wales and south-west England

There are now yellow weather warnings for: The rest of the UK.

For the latest on your area, visit the Met Office website., external

Image source, Getty Images

Scottish transport networks are running reduced services or not at all as they deal with more heavy snow:

• Edinburgh airport is closed
• Glasgow airport is closed until 15:00 GMT and advising passengers not to travel to the airport
• Lothian buses are all suspended with exception of Air link
• Edinburgh Trams are operating a reduced service through the city
• Scot Rail is only running services from Aberdeen to Inverness and Dundee, and from Inverness to Perth and Kyle of Lochalsh and Wick
• Virgin Trains is not running any trains between Carlisle and Scotland and there are no replacement buses
• Traffic Scotland are continuing to advise people not to travel on the roads

Get the latest updates for Scotland here.

Image source, PA

Paddington station has closed due to the amount of snow inside the station and ice on the platforms.

National Rail says at the moment, it doesn't know when the station will re-open.

Lesley Forster was stuck on the M80 in Scotland for 17 hours yesterday and this morning.

“I was driving from Edinbrugh to Mollinsburn," said Ms Forster. "I left Edinburgh at 2pm on Wednesday and have just arrived home at 8am on Thursday morning.

"I had nothing with me. I had to use the water I had with me to put in to my window wipers.

"I was stuck for 17 hours and have never been so frightened in my life. It was freezing cold. I had a total meltdown.

"There were no snow ploughs or anything.

"A young lad came out of his house with a sled filled with water and a few bits of food – all he had in the house and handed it out. I am so grateful to him.”

Simon King
BBC weather presenter and meteorologist

Motorist Nicola Lee was stuck overnight on the M80, which she described as looking "like a car park".

Entry to the M80 is now closed.

Jonathan Beale
BBC defence correspondent

The RAF is helping the NHS in Lincolnshire - transporting medical staff to hospital and helping others reach vulnerable patients trapped by the snow.

"We have 10 4x4's transporting healthcare workers so they can get to work in hospital," an MOD spokesman said.

"They will also take people to vulnerable patients so they can be seen and they will transport important medical supplies."

The Met Office has upgraded its amber weather warning to red in south-west England and south Wales.

A red weather warning is the most serious kind of weather warning that the Met Office can issue.

It means that risk to life is likely and that the weather will cause damage - for example, to buildings and roads.

Edward Rowe
BBC Radio Guernsey

Despite flights being able to land and take off on Guernsey Airport's runway, it will remain closed until 13:00 as a precaution, the airport says.

The band of heavy snow coming up from the south missed the islands overnight, but more is forecast at about 09:00.

Ports General Manager Colin Le Ray said: "We are liaising with the airlines to advise them of our plans and will update the situation at or just after 09:00 when the front passes over."

Glasgow Airport will be closed until 15:00 GMT.

This video was recorded just before 07:30 this morning.

BBC Weather Watchers

Our faithful Weather Watchers have been out snapping the wintry weather this morning.

Maria in Somerleyton, Suffolk, captured this cool character wearing a very sensible hat:

Image source, Weather Watchers

Shaz in Dunstable, Bedfordshire, saw the heart-warming side of these early morning tyre tracks:

Image source, Weather Watchers

And Hopping Frog in Sheringham, Norfolk, sums this week up pretty nicely:

Image source, Weather Watchers