Brits have been warned they must still get full travel insurance for trips to the EU from January 1 - despite the UK getting a Brexit deal.
The 1,246-page agreement means Brits will be able to get emergency healthcare while on holiday, like they can under the European Health Insurance Card.
People’s current EHICs will continue to be valid until they expire or are cancelled. They will then be replaced with a UK Global Health Insurance Card (GHIC).
The UK is in talks about further co-operation with non-EU states Switzerland, Iceland, Liechtenstein and Norway.
But despite this, Brits are being warned they must get comprehensive cover anyway if they are planning a trip to the continent.
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Officials say that is because EHICs only ever covered certain types of healthcare - in other words, emergency or necessary care.
The Brexit deal doesn’t cover Brits who travel to an EU country “with the purpose of receiving” healthcare - except for a limited number of exemptions.
Cabinet Minister Michael Gove has also urged Brits to check their mobile roaming policies, as firms will be free to reimpose roaming charges on Brits in the EU.
And he warned businesses time is "very short" before the “disruption" of new customs and single market checks kick in from this Friday.
There will be no tariffs or quotas on goods traded with the EU, but hauliers and even individual Brits sending packages will need to make customs declarations.
That is because Britain is leaving the EU’s single market and customs union.
"In just three days' time the Brexit transition period will end and we will have finally regained our independence," Mr Gove said.
“We know that there will be some disruption as we adjust to new ways of doing business with the EU.
“So it is vital that we all take the necessary action now on gov.uk/transition to ensure we are as ready as possible.”
Business owners must sign up for an EORI number from HMRC to import or export goods.
They will also need to check what new licences and certificates they may now need. Firms will also need to check the rules for importing alcohol, tobacco and certain oils
Mr Gove admitted British firms should be braced for “bumpy moments” when the Brexit transition ends on Friday.
He said Brits should make sure their passports have at least six months left before expiry if they want to travel to the EU.
There are a host of other things that change this Friday - click here for the full guide.
Tory Eurosceptics were urgently poring over the details of the treaty brokered on Christmas Eve and are expected to give their verdict on Tuesday.
In Brussels, European ambassadors were due to start the process of approving the post-Brexit trade deal this morning.
But in Britain there was growing anger among fishermen who fear they will be "absolutely worse off" as a result of the Government's deal with the EU.
National Federation of Fishermen's Organisations chairman Andrew Locker said the industry had been "betrayed" by the Prime Minister.
“ Boris Johnson promised us the rights to all the fish that swim in our exclusive economic zone and we have got a fraction of that,” he said.
“We are absolutely worse off. When we were within the EU we used to trade fish with the EU.
“We used to swap things we didn't use with fish that they didn't use and that enabled us to put together an annual fishing plan.
“What we have got now is a fraction of what we were promised through Brexit.
“We are going to really, really struggle this year.”
