If you are arriving in France either at Charles de Gaulle airport, or by Eurostar at Gare du Nord station, a pleasant alternative way to travel south is via the TGV to Montpellier or Beziers then pick up a hire car!
From Paris Charles de Gaulle head into Paris on RER (Blue) to Gare du Nord and from there on the Metro or via cab to Gare de Lyon. From Gare de Lyon take a TGV south towards Lyon / Montpellier! (journey time is usually about 3.5 - 4 hours) The Montpellier TGV usually goes on to Beziers and both train stations have good car hire options - check opening times for the car hire offices as the Beziers office hours vary. Also try and book your train tickets in advance if possible as this is always much cheaper!
From Beziers Station head north out of town towards the D909. Keep on the the D909 and follow this road north for approx 25km passing towns such as Magalas, Laurens and Faugeres. The D909 will take you into Hérépian, at the roundabout in Hérépian take the first exit towards Bedarieux (D908) and then take the first turning left on to the D922 Avenue René Cassin. Follow this road for approx 2.5km until you reach the sign for Villemagne L’Argentiere.
After the sign, take the right fork onto Avenue du Rampart and then immediately turn right down towards the river and over the low concrete ford bridge. Once over the bridge turn left and follow the single track road - you will have the village on your left on the opposite side of the river. Follow the road as it climbs up to the right and left. At the first fork in the road take the left hand track down and follow this for approx 100m where you will see the stone gate posts of Chemin du Jardin Haut.