To commute from the CDG Airport into the city of Paris, you would take Line B of the local RER train to the St. Michel stop. The RER trip from the airport to St. Michel would take about 40 to 45 minutes in duration. At the St Michel station, you would connect to Metro 10, which you would take directly over to the Austerlitz station, where trains to La Souterraine depart from. The ride on the Metro from the St. Michel station to the Austerlitz station only takes about 5 to 10 in duration. You would pay to board the RER and the Metro locally upon arrival.
You can purchase tickets for trains from Paris to La Souterraine under 'Find Fares & Schedules' or 'Check Fares and Schedules' on the homepage of our website, www.raileurope.com. Trains in France can be booked within 90 days of an intended date of departure.