Are you intending on heading to the BVI with the boat? If so, you can get a temporary certificate pending the survey and do the survey upon arrival in the BVI. There are several surveyors who will do the tonnage survey there. It might be possible that the BVI will accept a "British Tonnage Survey" and there are many such accredited surveyors in France
I did something similar with the British registry as I couldn't find an approved surveyor
when I picked up the boat (except one, who demanded that the boat be hauled for the survey, which is not necessary) so I used the temporary certificate until I was in the BVI and got the survey done, about $200 if I recall
and the surveyor going around the boat with a tape measure and bits of string. A week later I had my final paperwork.