But many would-be travelers faced a very significant problem: They didn't know exactly where they were allowed to go.

As the first people began checking in to their flights at the country's main airports, not even members of UK government seemed to be exactly sure of the situation.

At the heart of the confusion is a supposedly simple "traffic light" system that ranks destinations according to Covid-19 risk. Those designated red are no-go. Amber countries are sort of no-go. Green countries are OK, but only if they're open.

Add to that an extremely costly regime of testing, reams of paperwork and quarantine rules that differ depending on the category -- plus a passport control system that has come under fire for riskily mixing red and green country arrivals.

Travelers and those in the travel industry are resigned to more weeks of uncertainty as they try to make sense of the new rules.

It's all "very confusing," says Reigo Eljas, trading director of travel booking website LastMinute.com.

To travel or not to travel, that is the UK question

Under the traffic light system, 12 countries and territories are currently open to Brits without the need to quarantine on return. Of these, the only traditional mass tourism destinations where vaccinated or tested UK residents can easily visit are Portugal, Iceland, Gibraltar and the Faroe Islands.

Australia, New Zealand and Singapore make the UK's green list, but they aren't welcoming British residents currently. Meanwhile, Israel; Brunei; the Falkland Islands; South Georgia and the South Sandwich Islands; St. Helena, Ascension and Tristan da Cunha aren't exactly vacation hotspots right now.

Most of Europe's top destinations, including France, Greece, Italy and Spain, currently sit on the amber list. In theory, Brits can go there so long as they're prepared to quarantine on their return.

Or not.

On May 17, as the travel restrictions were lifted, UK Environment Secretary George Eustice told the BBC that people were now free to travel to amber countries "either to visit family or indeed to visit friends."

But hours later, UK Prime Minister Boris Johnson slammed the brakes on. An amber country, said Johnson, was "not somewhere where you should be going on holiday, let me be very clear about that." He added that people should only travel to an amber destination for "some pressing family or urgent business reason."

Government officials, including Transport Secretary Grant Shapps, have added further confusion by urging British residents to consider avoiding even green destinations because of growing fears about the risk from the Covid variant first identified in India. It is advice recently echoed by the World Health Organization.

While the government has promised to regularly review the traffic light list, there are no certainties. And with the school summer holidays just weeks away, some travelers are either confused by, willing to gamble on or simply prepared to ignore the prime minister's exhortations.