The first Christmas getaway for two years has led to high demand for leisure journeys by road, rail and air.
A survey of nearly 2,000 people in Britain for watchdog Transport Focus indicated that 44% plan to travel to visit friends or family over the festive period.
Coronavirus restrictions meant many people missed out on such visits 12 months ago.
The poll suggested the majority of those planning a getaway this year intend to travel by road, with only one in 10 using public transport.
An estimated 4.1 million journeys by people embarking on overnight stays or day trips will take place on UK roads on Thursday, rising to 5.3 million on Christmas Eve, according to RAC analysis.
Major roads are likely to be particularly busy between 12pm and 4pm on Thursday, and 11am and 2pm on Friday.
The RAC, which surveyed 1,400 drivers, predicts it will be the busiest Christmas getaway on the roads in five years.
Although demand for rail travel is at around 50% of pre-pandemic levels, thousands of people are travelling by train to spend Christmas with loved ones.
Hundreds of trains have been cancelled due to pandemic-related staff shortages.
Some 370 engineering projects are being carried out on the railways in the coming days, which will also disrupt services.
Heathrow Airport will be cut off from the rail and Tube network on Christmas Day and Boxing Day due to Network Rail and Transport for London doing simultaneous work.
Disruption elsewhere includes:
– Leeds will have a reduced service between December 27 and January 3, including a “very limited” service on January 2.
– No services will run between London King’s Cross and Finsbury Park on Christmas Day or Boxing Day.
– CrossCountry trains will not call at Bristol Parkway between December 27 and 31.
Passengers can find out whether their journeys are affected through their train operator or National Rail Enquiries.
👷 We've planned essential engineering works over the #Christmas and New Year bank holiday period to give you better services for the long term.🎄
— Network Rail (@networkrail) December 20, 2021
The festive period is one of the busiest times of the year outside summer for international travel from the UK, with many people visiting family overseas, enjoying a winter sun holiday or going skiing.
The number of people heading abroad is higher than last year but remains down on pre-pandemic levels.
Gatwick Airport said it expects to welcome nearly 750,000 passengers between December 18 and 31, which is nearly seven times more than over the same period 12 months ago but less than half of what it saw before the virus crisis.
Thursday and Boxing Day are expected to be among its busiest days for departures, with up to 35,000 passengers each day.
Popular destinations include the Irish capital, Dublin, and Cancun in Mexico.
Gatwick’s chief commercial officer, Jonathan Pollard, said the airport is “encouraged by the number of people looking to travel this Christmas” but said new coronavirus testing requirements have “impacted some people’s travel plans over the holiday period”.
He added: “While we understand the need for measures to stop the spread of the Omicron variant until more scientific information on its level of harm is available, it is vital these are in place no longer than absolutely necessary.”
Bristol Airport is anticipating it will be used by more than 100,000 passengers between December 21 and 31.
One of its busiest days will be December 27 when approximately 12,000 passengers will fly in or out of the airport.
Liverpool John Lennon Airport said it expects around 40,000 passengers to pass through between Christmas Eve and January 3, which is around 40% of pre-pandemic levels.
The airport was hoping demand would be at around 70%-80% of normal before the new restrictions were introduced.
Eurostar and Brittany Ferries both told the PA news agency they experienced an increase in cancellations after France announced a ban on UK arrivals for tourism and business trips last week.