We're going on a barge trip in June too! We'll be in the South of France though. I haven't read any comments on acquiring TGV tickets. We have our travel agent secure reservations in 1st class on the TGV before we go. I think they go on sale one month (at least) before departure. I'm glad we had them last year as the train was packed! This system is very different than travelling by train in Italy where we have the hotel concierge secure tickets for us.