Travel firms have seen a surge in demand following the announcement that restrictions on people returning from foreign trips are being eased or limited.
Train operator Eurostar said bookings on its London-Paris route doubled after it was confirmed that fully vaccinated arrivals from France will no longer need to self-isolate.
Online travel agency Skyscanner recorded a 45% increase in visits to its website after the announcement was made at 10pm on Wednesday, compared with an hour earlier.
Airline Emirates said it has received a “huge surge in queries” due to the decision to remove the United Arab Emirates from the red list.
The changes to the travel rules come into effect at 4am on Sunday.
The UK Government announced the changes for England, and the devolved administrations in Scotland and Northern Ireland said they will follow suit.
But the Welsh Government has not confirmed whether it will take the same action.
Transport Secretary Grant Shapps predicted that coronavirus vaccines will become a permanent requirement for international travel.
He told BBC Radio 4’s Today programme: “I think double vaccination, full vaccination, is going to be a feature forever more, and most countries, probably all countries, will require full vaccination in order for you to enter.”
The Cabinet minister explained that the rollout of vaccinations in the UK and overseas means changes to the travel lists are being made every three weeks, compared with once a week last summer.
He told Today: “I hope people will be able to go away under this simplified system, enjoy their breaks and not be looking over their shoulders the whole time.”
But asked on Sky News whether Spain could be put on the red list in future, the Cabinet minister replied: “With coronavirus you can never say there is zero chance.”
Meanwhile, Mr Shapps defended the decision to raise the price of quarantine hotels, which are mandatory for travellers returning to the UK from red list locations.
From August 12 the rate for solo travellers will rise from £1,750 to £2,285.
Additional adults sharing a room will see their bill hiked from £650 to £1,430.
Mr Shapps told Times Radio: “It is necessary to cover the costs of the quarantine hotels and at the moment the system hasn’t been doing that and it has cost about £75 million, so we are keen to ensure people using them are covering the full cost of this service.”
Under the latest changes, India, Bahrain, Qatar and the United Arab Emirates are being moved out of the red list, while Mexico, Georgia and the French overseas territories of La Reunion and Mayotte are being added to that tier.
A couple have told how they had to cut short their honeymoon in Mexico from two weeks to two days following the announcement to avoid having to stay in a quarantine hotel when they return.
Joe Coward, 29, from London, told the PA news agency: “We feel extremely angry at the Government’s incompetent handling of international travel rules during this crisis, and incredibly sad and frustrated that the time that should’ve been spent enjoying being newlyweds has been ruined.”
Emirates’ chief commercial officer Adnan Kazim said: “We’ve seen a huge surge in queries from customers desperate to travel to see their families, planning their kids’ return for the new school term, as well as their postponed business or holiday travel.”
Austria, Germany, Latvia, Norway, Romania, Slovenia and Slovakia will be added to the green list.
France is being aligned with other amber countries, which means fully vaccinated arrivals from the country will not need to self-isolate at home.
A Eurostar spokeswoman said the operator will be “welcoming more passengers on board as early as this weekend” and is “ready to further increase capacity over the coming weeks”.
Spain has avoided being given red status, but the Government is advising travellers to take a PCR test before they fly home from the country, rather than cheaper lateral flow tests.
Meanwhile, the number of people in England and Wales being told to self-isolate by the NHS Covid app has fallen dramatically.
A total of 395,971 alerts were sent in the week to July 28, down 43% on the previous week.
Experts said the main reason for the drop is the fall in virus cases.
A total of 189,232 people in England tested positive for coronavirus in the week to July 28.
The figure is down 39% on the previous week, and is the first week-on-week fall since early May.
Latest Government figures show a further 86 people had died within 28 days of testing positive for Covid-19 as of Thursday, taking the UK total to 130,086.
Separate figures published by the Office for National Statistics show there have now been 155,000 deaths registered in the UK where coronavirus was mentioned on the death certificate.
As of 9am on Thursday, there had been a further 30,215 lab-confirmed cases in the UK.