A £250,000 scheme has been set up by the Diocese in Europe to assist UK nationals living in France with residency permit applications.
Britain formally left the European Union at the start of the year and the official transition period is set to end on 31 December.
Under the terms of the Withdrawal Agreement, UK nationals wishing to remain legally resident in the EU are required to obtain "settled status" by June 2021.
There are an estimated 1.3m UK nationals living in the EU, with over 400,000 in France.
Bishop in Europe, Robert Innes, said the prospect of applying for residency was a "daunting" one for many UK nationals living in France.
"The ability to remain legally resident has been the biggest post-Brexit concern among people who have contacted our diocese over the past year," he said.
"I recognise the prospect of applying for residency is a truly daunting one for people right across the diocese, particularly when deadlines are tight. And it can be particularly tough for older and isolated people, for whom our service is especially intended."
He added: "Let me emphasise, too, that the Diocese in Europe is offering a service to all. We're not just here for those who might join us at a Church service. And we look forward to you being in touch."
The Diocese in Europe Residency Support Project has been made possible by the UK Nationals Support Fund Programme administered across the EU by the UK Foreign Office.
A dedicated website and helpline will signpost UK nationals to the latest advice from the UK and French Governments free of charge.
Additional services, also free, include casework support on residency applications.
The project will have a particular focus on over-65s and those living in the Nouvelle-Aquitaine region, which has the highest proportion of UK nationals in France.
Damian Thwaites, who represents Bishop Innes at the EU, has been leading the development of the diocesan project.
He said: "Our launch marks a key implementing step for work that began last September to plan and prepare a project bid, particularly around the constraints of Covid-19, and negotiate a delivery contract.
"From the start, we wanted to focus effort on the people whose needs would be greatest, supported by our network of Anglican chaplaincies and congregations that could have the biggest impact in helping UK nationals to apply for residency.
"The huge amount of work that has gone into digital project design, delivery and operational set up by our initial project team, in such a short space of time, has been fantastic."
In a video message to the Aquitaine Chaplaincy, the Rev Tony Lomas said: "For all of us who are resident in France, [Brexit] is going to mean something of an administrative upheaval and we will all, without exception, be required to obtain a new residency permit."
He added: "It's really encouraging that our Church is taking such a pro-active approach to helping the British community in Nouvelle-Aquitaine."