I've researched all the other legs of our trip via public transportation but have not been able to find solid information on how to get to Mont St Michel from Versailles. I'm hoping someone might be able to point me in the right direction!
Our itinerary so far is to arrive on a Monday morning at CDG, take the train from CDG to Paris, transfer at St Michel/Notre Dame to C5 and arrive in Versailles at Rive Gauche. We will be staying in a nearby hotel for 2 nights.
On Wednesday around noon we will be heading to Mont St Michel for an overnight. Originally I thought we might have to take the train back to Paris and then catch a different train to Rennes, but it looks like the line leaving from Gare Montparnasse passes through Versailles via Versailles Chantiers station, but I have not been able to figure out if the train to Rennes will be stopping there or not. I know there are only 4 trains a day from Gare Montparnasse to Rennes, and according to raileurope.com there is one that leaves from Paris at 12:25pm, but nothing from Versailles.
Will we have to buy our tickets for Rennes a few days in advance or can we buy the tickets the day of? I don't clearly know the differences between all the rail lines and companies in France yet.
As I understand it, once I figure out how to get out to Rennes by train, there will be a bus to catch for the last 90 minutes of the trip out to the Mont. We will be staying overnight at Hotel Vert near the causeway. We plan to see the Mont at night and the next morning and catch the bus -> Rennes -> Paris probably around noon or early afternoon. We will then be spending the remaining 8-9 days in Paris where things will be much simpler =)
Thanks for any help!