I'll tell you what we had to do, and hope it helps you a bit. My husband and I are both UK nationals. We bought a maison secondaire in Deux-Sevres almost 10 years ago, then in 2006, after a New Year 'suggestion' by the Maire, we decided to get married in our little French village. The Maire checked with the Prefecture in Bressuire, and, as we paid full taxe fonciere and taxe d'habitation we could be considered as resident in the commune (although we weren't). We booked him, and the salle des fetes before doing anything. Then we published our banns at our local register office in UK. Once we received this document of 'no impediment' it went into our pile of documents which would need to be officially translated - here is what we had to have translated:
Both of our UK birth certificates.
My FIRST marriage certificate
Both of our Decree Absolutes
A colour copy of each of our British passports.
Plus a colour copy of each of the passports of our four witnesses (all UK nationals) plus for each of these witnesses a letter, on official headed notepaper, from their employers saying they were 'upstanding, known employees of long-standing'
A coy of our 'certificate of no impediment'
AND we had to have blood tests and a medical - medical by a local French GP, blood test at the local laboratoire analyses (God knows why - I was not of child-bearing ability, so why blood tests - I blame Napoleon!!).
We had ALL our documents translated by a local (in UK) independent official translator, working for a translation company in UK - it cost about £10 a document then.
Then we brought all this over to France with us, and presented it at the Mairie, and about four weeks later we had a letter saying that our French marriage could go ahead!!
It was the most stunning and wonderful day of our lives together (and we've been together 21 years now). We had about 30 friends and family over from the UK (who were all accommodated by our friends in the village, both French and British}, and about 60 of our French friends from the village for the ceremony at the Mairie and the 'vin d'honneur' at the salle des fetes afterwards (no churchy blessing for us). Then we went for a stunning reception meal which went on four almost five hours at a nearby lakeside restaurant Then, in the evening we had invited the whole village to our buffet dance, with French country dancing, disco, and singing from both the French male (club de footl) crew and the UK male rugby crew - very funny and in great good humour. We had the onion soupe from a 'potty' (or guz under, as we say in the North) at about 3.00a.m and everyone went home inebriated and very happy. We made the national newspapers - la Novelle Republique and another one (I forget now which one) as we were such a novelty act at the time!!
We now have our Livret de Famille which has space in it to record about 8 children - again, they are being very optimistic. I am 57 now!!
The only other thing I have yet to do is register our French marriage certificate along with our UK banns at some official repository some where in the UK - but not sure where!
So, it is a lot of hard work, but all I can say is Je ne regrette rien et Bon Courage