Video report by ITV News Political Reporter Shehab Khan
People have been warned to consider their Covid Christmas travel plans - and even factor in not travelling home for the holiday.
It comes as the four nations meet to thrash out how to allow families to reunite over the festive period.
ITV News' Political Editor Robert Peston understands a five-day easing of the rules with allow for up to three families to spend the Christmas period together.
A Cobra meeting with the UK government and the devolved administrations of Scotland, Wales and Northern Ireland will be held on Tuesday afternoon to agree on a four-nation approach to relaxing coronavirus restrictions over the festive period.
Ahead of the meeting the Prime Minister’s official spokesman said: “We have been clear of our desire to try and agree a four-nations approach which will allow families to meet up over the Christmas period.”
Agreement has not yet been reached and it is not clear whether the Cobra meeting will provide certainty for families planning their Christmas break.
But the Number 10 spokesman said: “We continue to work with the devolved nations to agree a plan to allow families to meet up over Christmas.
“That work is ongoing and there will be a meeting later of Cobra to discuss it."
Prime Minister Boris Johnson is determined to give families the chance to meet at the end of a grim year but acknowledged it was not without risks. Health Secretary Matt Hancock said that Christmas would not look the same as normal as he urged people to “respect the spread of the virus”.
Dr Sarah Jarvis on her concerns over households mixing over the Christmas period
Ahead of the Cobra meeting chaired by Cabinet Office Minister Michael Gove, Scotland’s First Minister Nicola Sturgeon said it was hoped they could agree a “common framework” across the UK, although there may be some regional differences, including the definition of a household – to “reflect the different circumstances in each nation”.
She said: “I know everyone has a desire to see loved ones over the festive period.
“However, there is also a very real and a very legitimate anxiety that doing so could put those we love at risk, set back our progress as a country and result in unnecessary deaths and suffering.”
Even with festive season relaxation, people are being warned to “look very carefully” at how they will go home for Christmas.
Welsh First Minister Mark Drakeford said there would need to be a cautious approach both before Christmas and in the “aftermath” because of the risk that increased household mixing could spread the virus.
Earlier, UK Transport Secretary Grant Shapps said: “We have got to understand there are limitations to the (train) network caused by, for example, things like the need on some trains to pre-book tickets at this time, in order to prevent overcrowding,” he told the BBC.
“So we are going to be appealing to people to look very carefully at the transport route they take and of course even making a choice about whether they travel at all.”
ITV News Political Editor Robert Peston says it is "looking highly probable" that special Christmas exemptions will allow us to socialise with people from three households over five days beginning on 23 December and ending on 27 December.
ITV News Political Reporter Shehab Khan on what could be discussed at the Cobra Christmas crunch meeting
In England, the government has already announced new tiered restrictions which will come into effect on December 2 and could last until the end of March – aside from any Christmas relaxation.
On Thursday, people in England will find out which tier they are being placed in once the lockdown ends. The Joint Biosecurity Centre will make recommendations of which areas of England should be placed in which tier from December 2, Downing Street has said.
What can you do in each tier from December 2? The new rules in England at a glance:
Tier 1: Up to six people can meet indoors or outdoors. Pubs and restaurants can open, with last orders at 10pm and closing at 11pm.
Tier 2: No mixing indoors, apart from support bubbles. Up to six people can meet outdoors. Pubs and restaurants can open, with last orders at 10pm and closing at 11pm - but alcohol can only be served with a substantial meal.
Tier 3: No mixing indoors. People can only meet outdoors in limited places such as parks and public gardens. Pubs and restaurants must close, with the exception of takeaway sales.
In all tiers, non-essential shops, gyms, hairdressers and personal care services can open.
People in all tiers to work from home where they can do so. Full details on what you can do in each tier here.
More regions than before the lockdown are expected to face Tier 2 or Tier 3 restrictions, banning simple acts such as popping to the pub for a pint of beer or a glass of wine.
In Tier 2, alcohol can only be consumed with a “substantial meal” while in Tier 3 pubs and restaurants will only be able to offer takeaway or delivery services.