In reply to BusyLizzie:
I live in France and have done quite a few races - as part of my running club I get a licence which takes the place of the certificate (i just give the race my licence number) but every 3 years I need a real certificate from my doc. It seems ridiculous (eg. whatever happened to personal responsibility, and also why put obstacles to people taking part in physical exercise?) but the French think we're the weird ones.
When I lived in the UK and raced in France I had to get one and most doctors (10 years ago mind) would freak out thinking they would get sued if I collapsed mid-race, suggesting in-depth scans (I've heard of people being forced to undergo full private medicals before their GP would sign).
In the end I got our company GP who visited the office every month to write one out. The wording basically needs to say that you 'show no contra-indications to running' - it doesn't say you're necessarily fine, just that there's no obvious impediment. I don't think the race organisers will look into it, in fact I don't think your doctor would give out any information anyway due to patient confidentiality. All they will look for is an official looking GP stamp (the official stamp is important and not as common in the UK) and a signature that looks like a dying spider crawled through some ink (so it look like a real doctor).
Although my UK sourced certificates were in English they were accepted in France. But best if your race organizer can offer one to download.
Luckily, the certificate can be reused in multiple races and is valid for one year.
Good luck, with the admin and the race/training.