French fittings are usually metric but you will find 1/2 3/4 etc imperial fittings since these still seem to be standard for many appliances, for instance ch radiators, taps.
Browse the shelves of your local Catena, Brico Depot or Leroy Merlin etc.
Having found the site interesting and informative thought it about time I made a small contribution!
http://www.saep.fr/fr/3_bricolage/24_delta-2000-pratique-bricolage.htm