lord hereford,
I got a doctor's note without charge from my NHS GP. We came up with the following wording during the 15 minute consulation where he took my blood pressure and asked me if I did much cycling:
Dear Mr Brymbo,
I can confirm that you are fit to take part in the Cyclosportives et Grand Trophee event in July 2008.
There are no contra-indications for you to take part in a cycling competition for the next year.
As you can see, the note was addressed to me. It was printed on the practice's stationery, bearing their name etc. If you want to see a scanned PDF copy then pm me with your email address.
I replied to the "Grand Trophee Inscription/Registration" email I received from sportcommunication with the scanned PDF and this text, signed off with my name and dossard (entry number):
Bonjour,
Je vous envoi mon certificat médical en pièce jointe de ce mail.
En espérant le bonne réception de celui-ci.
A bientôt
I then took the original document with me and showed it when registering in person in Alpe d'Huez the day before the event.
Maybe over the top, but I'm a bit of a fretter and prefer both belt and braces.