The Facebook group Applying for a French Driving Licence is an excellent resource for those exchanging not only UK licences, but also licences issued by other countries.
The group is archived every Friday at 12.00 until Monday 14.00 and all bank holidays, France & UK so may not be visible when you click the link.
To join you must be resident in France as documents required to apply can only be obtained once you are here.
Please ensure you complete the joining questions.
You'll find an overview here.
United Kingdom Nationals Support Funds (UKNSF)
The UKNSF, launched in March 2020, provided practical support for UK nationals resident in EU or EFTA countries who needed additional assistance in applying for residency.
The funding has now ended but you can read about those who provided support and find links to their websites here.