GTV to Bayonne?

[sou]

Hello everyone from Japon,
I'm thinking of trying the camino from SJPDP to Logrono in 7 days this August. I'm a beginner to challenge the camino.
Could anyone give me any advices or answers to my questions below?
1.How much is theTGV fare from Paris to Byonne? I'm a sinior.
2.Isn't it quite difficult to get the ticket during summer season particularly because of a holly year? I would like to get it at Montparnasse station 'cause I don't want my schedule is fixed.
3.I think there will be a thousands of pilgrims in SJPDP in summer. Are there any possibilities I can't saty at albergue or hotel? If so, what should/can I do?
I hope you kindly try to understand what I mean written in poor English.
ARIGATO!

Ooops! I've posted this into wrong place. I'm sorry. I have noticed that I don't know how to use this forum.
Could anyone help me?