Take the D31 towards Amboise, Cross the Loire river
Stay on the D31 (which bypasses Amboise) towards Bléré.
Continue on the D31 towards Loches.
After St Quentin sur Indrois, pass through Loches forest.
At the roundabout, follow Loches.
At the 4th roundabout, take the right D943 towards Tours.
Travel then about 3 Km, take the road on the right : it's a narrow road, situated behind an isolated corner house, towards la Bernardière, la Quellerie. The sign is not obvious : you'll only see it on your right after you have turned, it's also at the Milepost 19.
Keep going, cross the railroad and continue to the end of the road on the right (dead-end) until you get to the fence. You're arrived.
IF YOU USE A GPS :
please do not enter Isle Auger because it will lead you to arrive by the wrong side of the river.
Instead use the GPS coordinates or search "Loches rue de la Fontaine Charbonnelle" which will lead you to the road D943 toward Tours, then follow the above information.
How to come to Isle Auger by train?
PARIS -TOURS : TGV (Railroad company SNCF) : 55 minutes
Departure : PARIS Montparnasse railway station
Arrival : TOURS railway station - ST PIERRE DES CORPS
Shuttle : St Pierre des Corps - TOURS CENTRE
Then train or bus link TOURS CENTRE - LOCHES (company SNCF)
Departure : Railway station or Bus station of TOURS
Arrival : Railway station or Bus station of LOCHES