This Easter is set to be one of the busiest on the roads "for several years", the AA has said.
Around 10 million cars are set to take to the roads over the Easter holiday, according to AA Roadwatch and traffic information company Trafficmaster.
And a further eight million cars will be on the move over the royal wedding weekend at the end of the month, the two organisations forecast.
An AA/Populus survey of around 13,000 AA members showed that 85% were planning to stay in the UK over the Easter and royal wedding bank holiday periods. A third are planning to make car trips over Easter, with those in Northern Ireland the most likely to take to the road, while the Scots are the likeliest to stay at home.
AA patrolman of the year Paul Leather said: "Our research shows that Easter will be the busier of the two bank holiday weekends, as the schools are still out. We expect congestion to peak on Maundy Thursday, April 21."
Trafficmaster said there would be more of a staggered getaway than usual as Easter falls at the end of the school holidays.
The main getaway is expected to start in earnest this weekend as people will only have to take four days off to get an extended break. Friday is expected to see a busier evening rush hour as people head off early, with traffic remaining heavy over the weekend, especially in London and south-east England, with FA Cup semi-finals at Wembley and the Virgin London Marathon on Sunday.
By Easter, the Highways Agency will have completed a number of works on England's motorways and major A roads and will be suspending 144 miles of work at other sites.
The suspension will be from 6am on Thursday April 21 until midnight on Monday May 2. But works will remain in place at 22 locations, including a section of the M25 near St Albans in Hertfordshire and the M1 near Luton in Bedfordshire.
The RAC warned that roads around theme parks, shopping centres and retail outlets were likely to be busy over Easter. RAC patrol ambassador Kevin Andrews said: "People need to plan their journeys before setting off. Allow plenty of time for your journey particularly if you're heading for a popular resort or travelling at peak times."