From Paris, take the train at Saint-Lazare station and get off at Carentan. When you arrive in Carentan, you have to hire a car or hire a taxi.
From Cherbourg, take the train at the station and get off at Carentan. Otherwise, coming by boat with your car, there are 40 minutes to go to Carentan. Then you have to follow the direction of Sainte-Marie-du-Mont.
By road, take the Carentan exit on the RN13, then direction Sainte-Marie-du-Mont.