Brits could face seven-hour queues at the airport this summer due to coronavirus restrictions, experts have warned.
Foreign holidays will resume from May 17 at the earliest under the government's traffic light system.
Officials have said they will set out “by early May” the actual date when international travel can resume and £5,000 fines are dropped.
But, when trips abroad are allowed, experts have warned people should prepare for chaos as they head to the airport.
It is feared that the closure of digital e-gates will see border workers doing all checks manually even at peak season - which could extend queues.
As well as passports and other regulation documents, airport workers will have to check Covid forms and quarantine information.
Lucy Moreton, from the Immigration Services Union, said "six or seven hours" of waiting is not impossible in the worse-case scenario.
"If they don’t digitise the e-gates and they still require us to do 100 per cent checks, then yes the queues could potentially at busy times become even worse than they are now," she told The Sun.
And CEO of Airlines UK Tim Alderslade added: "Manual checks are time-consuming and will become increasingly challenging as passenger numbers increase, as we hope they will.
"This is why a fully digitalised passenger locator form is the way to go."
Under the holiday traffic light system, arrivals from green countries will not have to quarantine on return to the UK, unless they test positive or show symptoms.
But they must take two tests: a pre-departure test before setting off back to the UK, then a second gold-standard PCR test on or before day 2 after they arrive home.
Arrivals from amber countries will need to quarantine for 10 days, but they can do this at their home.
They must take three tests - pre-departure, and then PCR tests on day 2 and day 8 after they arrive home.
They can choose to pay for a fourth test on day 5, and if it comes back negative they can leave quarantine early.
This is called Test to Release.
Arrivals from red countries must quarantine for 10 days in a hotel at £1,750 a head.
They must also take three tests - the same as the amber group - and cannot pay for Test to Release.
It has also emerged in recent days that jet-setting families face a £120 bill to test their children for Covid - despite under-11s getting a special exemption in Britain's summer holidays scheme.
It's emerged under-11s will not have to take "pre-departure" tests before they return to the UK under the traffic light system for foreign travel.
But by contrast, only under-5s will be exempt from taking "post-arrival" tests after they arrive back in Britain.
It's thought children aged 5 to 10 will still have to take the gold-standard post-arrival PCR tests, which cost around £120 for one or £190 for a set of two according to Which?.
That could leave families with huge bills - with fears some parents may be dissuaded from travelling this summer due to the high cost.
People have been warned there is a "substantial risk" any foreign holiday plans they make this summer will have to change as the easing of lockdown progresses in the coming months.