We (my husband and I with our 6 grown children) are all arriving into Paris at diffent times and will be meet in the Loire Valley. We are flying into CDG airport. Is it necessary to purchase a train ticket in advance? They are not refundable one never knows about airline schedules. WE were looking at the high speed train from CDG. Or would you recommend going into Paris and catching the train there?
TGVs to St-Pierre-des-Corps depart CDG at 07:39, 08:58, 13:37, and 15:42. It's a five-minute ride on another train from there to Tours.
For more frequent service, go into Paris and either take a TGV from Gare Montparnasse (usually with a connection in St-Pierre-des-Corps) or a direct but slower train from Gare d'Austerlitz.
When will you arrive at CDG? If it's not on a French holiday, you should be able to buy tickets for any of your possible routes on the spot rather than having to do it in advance. However, you could play it safe and book in advance. Standard fare tickets are exchangeable so you're not out anything if your plane is late.
Discount fares are sold for these routes, but those tickets are non-exchangeable and non-refundable. If your plane is late and you miss your train, you'll have to buy a new standard fare ticket on another train.