Urgent clarity is being urged by Brittany Ferries on the date when returning holidaymakers can switch from costly PCR tests to cheaper lateral flow tests.
The measure, announced by transport secretary Grant Shapps last Friday accompanied by the end of pre-departure tests from October 4, will make an international holiday more attractive and less expensive for travellers.
Government says the aim is to have it in place for when people return for half-term breaks.
But without a clear deadline, travellers remain cautious, the ferry firm warned.
The company said: “The woolly aspiration – from the end of October – is not helpful.
“Holidaymakers and travel companies like Brittany Ferries need urgent clarification to release a dam of pent-up demand.”
Brittany Ferries reported a 71% rise in bookings for the October school half-term period and a 25% increase in forward reservations for 2022.
However, the company said many customers say they are waiting for “absolute clarity” over lateral flow test provisions before booking their next trip to France or Spain.
Sales and marketing director Paul Acheson added:“We welcome changes to the travel framework for fully jabbed Brits and we have seen a significant increase in reservations as a consequence.
“However, many families looking for a last-minute break are understandably still wary.
“We need government to announce a clear date upon which PCR tests will revert to lateral flow.
“This will release a dam of demand, supporting those working in the travel sector and giving holidaymakers the full confidence they need to book a last minute get-away.”