In a land just 20 miles from Britain, people can catch an international train just by buying a ticket and turning up. For Eurostar travellers from London it has never been that simple. But from 6 October, when the EU’s new border regime kicks in, a fresh headache of requirements will apply.

There may be some comfort in Eurostar’s promise that it “won’t be a shitshow”. It has spent a year discussing the precise requirements of the EU entry-exit system (EES), and invested €10m in revamping St Pancras International.

Here Benugo, an upmarket toastie purveyor, is being ejected from its prime spot to make way for rows of biometric kiosks. Passengers will have to upload their fingerprints and scan their faces, then walk – or queue – past the piano donated by Elton John to the ticket gates. Once they’re through those, the baggage screening and UK passport control, French border police will take their fingerprints all over again.

Eurostar says its modelling shows passengers will be able to complete the process within the recommended 60 to 90 minutes before travel, though some reports last week claimed it would take two hours.

Eurostar’s chief stations and security officer, Simon Lejeune, said: “We’re confident 6 October won’t be a shitshow because of the work that’s going in … we have the right set-up.”

The bar for what is regarded as a “shitshow” in Britain has been raised substantially since the 2016 referendum, but these increasing hurdles will make some travellers wonder if just staying home to watch Emily in Paris or Ratatouille might be easier.

For Eurostar, the key is capacity – or how quickly passengers can pass the frontier, and it is installing 49 kiosks in three areas: the other two are for business or premier passengers and an upstairs overflow set-up for when things get hairy at peak times. The double fingerprint check is necessary because biometric data collection must be supervised by a European border officer on first entry. After registration, people will be able to use e-gates for three years. France has agreed to double the police aux frontières booths from nine to 18.

Brexit had already cut capacity on trains to Paris, Brussels and Amsterdam: the stamping of paper passports was taking so long that trains were not able to fill up and depart on time. Now, Eurostar hopes to cut the last part of the border process from 59 to 37 seconds.

The Port of Dover has raised the alarm over how, in a constrained space, arriving car passengers can have all their biometric details taken by EU officials. The CPT, the trade body for coach operators, this week called on ministers for action, warning that EES would “inevitably add to processing time” at the port. Getlink, the Channel tunnel and Shuttle operator, has announced spending of about €70m on measures to avoid a launch-day meltdown.

The scheme has been delayed by concerns over back-end computing capabilities and staffing, and the French lobbied hard to put EES back until after the Paris Olympics.

For Eurostar, Le Shuttle and the Port of Dover, the French border is “juxtaposed” – physically in Britain – which means checks and queues come before actual travel. Richard Thorp, engineering director at HS1 Ltd, which operates St Pancras station, said: “Everything will be done in London, and when you arrive, you’re free to go. The challenge our airline friends will have is that all that EES process is on arrival.”

Airline passengers could find themselves on 6 October at, say, a small Greek airport which has not had millions invested in staff and kiosks to process biometric data. Passport queues for non-EU travellers may not be a pretty sight.

Airports remain concerned, not least because final confirmation of the start date is not expected until 28 August, the tail of the summer peak. Olivier Jankovec, director general of airports trade body ACI Europe, says border processing time will rise by up to 50% and adds: “A number of unresolved issues require urgent attention from the European Commission and states.” These include proper testing of the scheme; delays to a promised pre-registration app; and consideration of what border delays could mean. Jankovec says: “More needs to be done to ensure readiness also in terms of passenger awareness.”

What ministers call “precautionary flexibility measures” could apply for six months. They include, in Thorp’s words, “mechanisms to maintain a fluid process” – potentially waving people through just on passports if the system keels over.

EES will be followed some time in 2025 by the European Travel Information and Authorisation System (Etias), which will require British and other non-EU passengers to pre-register more details and pay €7 before crossing the Channel.

Standing by the doomed Benugo with a mocked-up EES kiosk, Thorp and Lejeune concur: “We don’t want to even think about that yet.”