Travel trade organisation Abta described the easing of restrictions as “a new chapter” for the industry’s recovery.
Meanwhile, Transport Secretary Grant Shapps said the scrapping of testing ahead of half term comes as “good news” for families.
“The UK has eased international travel measures for Covid-19 and now has one of the most free-flowing borders in the world – sending a clear message that we are open for business,” he added.
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Turkey, Egypt and Portugal are among the most popular short-haul destinations, while departures to the US state of Florida, Dubai, Mexico and the Caribbean have sold well for longer-haul holidays, according to Abta.
Ski resorts in France, Italy and Switzerland are also in demand.
Stansted Airport told Abta it is expecting around 200,000 passengers to depart between February 11 and 18.
Other airports to provide figures for the half-term getaway include Gatwick (186,000 passengers), Manchester (160,000 passengers), Luton (55,000 passengers), Bristol (55,000 passengers) and East Midlands (17,000 passengers).
The UK’s rules for arriving travellers were eased from 4am on Friday.
People who are fully vaccinated will no longer need to take a post-arrival lateral flow test, which typically costs around £20 each.
The requirement for unvaccinated arrivals to self-isolate will be dropped, but they will still need to take tests.
Andrew Flintham, managing director for TUI UK, said bookings for February half-term and Easter were now “comparable” to 2019.
“There remains a huge pent-up demand for international travel and we’ve seen strong and sustained booking patterns since the announcement as customers look to go abroad with ease and without the added expense of testing,” he said.
Sean Doyle, CEO of British Airways also welcomed the changes but added: “We hope that other countries will soon catch up with the UK’s pragmatic approach.”
A poll of 2,000 UK consumers commissioned by Abta indicated that 64% of families with children under 16 say the limited opportunities to travel during the pandemic have made their holidays more important to them than before.
The travel association’s director of communications Graeme Buck said: “Today’s changes to the travel rules are the start of a new chapter for the travel industry’s recovery.
“Testing has been one of the biggest barriers to travel, so it’s hugely welcome that the process of travelling abroad is now much cheaper and easier for millions of UK holidaymakers.”
Cross-Channel train operator Eurostar said more than 125,000 people are booked to travel between the UK and the Continent during the school holiday.
The busiest day will be Friday, when more than 16,000 passengers are booked to travel.
Several services are sold out.
Eurostar chief commercial officer Francois Le Doze said: “With travel restrictions between the UK and France lifting, we are seeing a surge in leisure traffic both in the short term and looking further ahead to spring and early summer.”
UK holidaymakers travelling abroad must still follow the coronavirus regulations that apply at their destination.
Spain’s requirement for children over 12 to be fully vaccinated led many UK families to cancel plans to visit the Mediterranean country over half-term.