The British Embassy may be able to help you if you have a problem relating, for example, to a passport application, a French Withdrawal Agreement Residence Permit (WARP), pensions or driving licences.
You should first look at the LivingInFrance guide which should give the information you need.
However, if this does not answer your questions, you can use the Embassy's contact form.
To submit your question, you click on the link above and put a short description of your issue in the box "What is your enquiry about".
If the suggested answers on the next page do not answer your query, you should answer "No, I would like to submit my enquiry" to the question "Do the suggested pages answer your enquiry?" at the bottom of the page. This will open up the contact form in which you can provide details of your problem.