(This is not a journey we do very often, so the instructions are a little more uncertain.)
Come out of Thuoars on the road towards Puy Notre Dame. At Bagneux cut across country to Nueil sur Layon. Keep an eye out for the town square (which functions as car park) and follow the road signposted to Passavant sur Layon.
Once you reach Passavant you will hit a T-junction. Your road is a narrow road between high buildings. Come out carefully and turn right. Follow this until you can see the castle ahead of you and turn left into a tarmac car park. You will see the gÃ®te straight in front of you.