BRUSSELS — Millions of Europeans have freely lived, worked and studied in the UK for decades, but Brexit means that those rights are no longer automatically granted. Britain's government introduced a "settlement" plan for the country's large European migrant community in 2019, and the deadline for applications is Wednesday.

From Thursday, any European migrant who hasn't applied will lose their legal right to work, rent housing and access some hospital treatments or welfare benefits in the UK. They may even be subject to deportation.

Wednesday is also the deadline for British nationals living in three EU countries — France, Latvia and Malta — to apply for residency. British in Europe, a coalition group campaigning for Britons living in the EU, has renewed a warning that people risk losing their rights if they do not do so.

The British government has warned EU nationals living in the country that they'll be handed a formal 28-day notice if they've failed to apply for "settled status" by June 30.

Campaigners are worried that tens or even hundreds of thousands of Europeans may not have applied by the deadline.

Many older people who have lived in the UK for decades are not aware they have to apply, and official figures show that only 2% of applicants were 65 years old or older.

Many parents also don't realize they have to apply for their children, migrants' groups say.

Other vulnerable people, such as children in social care, also risk falling through the cracks and ending up with no legal status.

Britain's government says well over five million people — the majority from Poland and Romania — have applied, far more than initial estimates.

While about half were granted settled status, some two million migrants who haven't lived in the UK long enough were told they have to put in the paperwork again when they have completed five more years of residency in the country.

Britain's Business Minister Anne-Marie Trevelyan said on Wednesday that the EU Settlement Scheme has worked well for those who applied, despite concerns by campaigners that many applicants are still in limbo awaiting their reply.

Speaking to Sky News, Trevelyan said it is a "phenomenal scheme", adding that although government processes can "be difficult, this one was a really effective and slick one for those 5.2 million people".

Lara Parizotto, a campaigner for The3million, a group set up after the Brexit referendum to lobby for the rights of EU citizens in the UK, has been leafleting and urging EU nationals to apply.

Figures are not available to show exactly how many people will have missed the deadline, Parizotto said. But even a small percentage of the European population in the UK would total tens of thousands of people.

Another campaigner, Elena Remigi, said she fears the policy could lead to a disastrous legacy similar to the Windrush Scandal, when many from the Caribbean who legally settled in the UK decades ago were wrongly caught up in tough new government rules to crack down on illegal immigration.

Many in the "Windrush generation" — named after the ship that carried the first post-war migrants from the West Indies — lost their homes and jobs or were even deported simply because they couldn't produce paperwork proving their residency rights.

Marlies Haselton has called Britain home for more than 30 years. The Dutch national married a Briton, had her children here, and considers herself "part and parcel" of the UK. Until Britain's divorce from the European Union, she had never given a thought to her immigration status in the UK.

For Haselton and many others, it's a moment that drives home the impact of Britain's 2016 referendum to leave the EU five years ago. Although Haselton successfully received her "settled" status, meaning she can reside permanently in the UK., she said the whole process has made her feel insecure about the life she built in Britain.

"I can't even get citizenship. It feels a bit like an insult because I'm part and parcel of this country. Really I'm part of the furniture. And I've lost that sense of home," said Haselton.

With only hours to go before the deadline, Lara Parizotto is racing against the clock to inform as many people as possible.

Student Kacper Adamus, 17, a Polish national who has lived in the UK for 10 years said he didn't have any issues applying for settlement.

"It was quite easy it didn't take much time. It was very easy for me to operate and I don't really have an issue doing it, it was quite easy so there were no problems," he said.

But for long term resident Haselton, there is a loss of trust. Her British husband is mulling moving the family to the Netherlands as a direct consequence of Brexit. She is torn.

"I still love this country, it would break my heart if I had to move," she said. "At the same time I'm not sure I want to stay." — Euronews