Hello traveling friends: We are spending a few weeks in France in April. On April 11 we are traveling from Paris to Marne la vallee Chessy station to transfer to a TGV train to Marseille (Gare St. Charles). I have those tickets in hand. I have the Bonjour RATP app on my iPhone and it appears we can go from our AirBnB on metro to Chatelet les Halles and from there via RER A to Marne la vallee chessy station. We have never been to the Marne La Vallee Chessy station and wonder if there are any special tips on getting there. Do I need to buy the RER tickets ahead of time? Or is this a commonly popular trip with the ability to buy tickets at the Chatelet metro station? Any info or tips are appreciated. Thanks in advance. Susan
PS I know that there is a lot of work happening on the metro lines and probably the RER lines as well due to the Olympics prep. So I will be taking that into planning consideration. I love the Bonjour RATP app which keeps me pretty well informed about disruptions and alternative routes. This will be an adventure!!