have lived apart from my wife for over 5 years and have lived in France for those 5 years.
Does anyone know if it legally possible for me to start divorce proceedings here in France even though the original marriage was in the UK and my wife has always and still does, live there?
At least you are in the correct time zone for this site's clock.
As long as you meet the French residency requirements you may apply there. You should be aware though that the country where divorce proceedings are first commenced will have jurisdiction so if you wife has petitioned in the UK the divorce will go ahead here.