to make reservation TGV?

Hello. I m going to have a journey from paris to toulouse
on 01/06

there are few thing that i need to check before i abroad.

Ive searched train section on voyage-sncf.com
from paris - toulouse and i should get a night train

(see below here)
”””””””””””””””””””””””””””””””””””’
Aller le vendredi 01/06 à partir de 22h56 - prix total pour 1 passager

Sélectionnez le tarif de votre choix puis validez votre aller
22h56 PARIS AUSTERLITZ
06h41 TOULOUSE MATABIAU

.”””””””””””””””””””””””””””””””””’
it’s ticket fares are

discovery 12-25 -> 65euros

regular fare - 86.60

————————

when i searched for the ticket,

i put ‘young person 12-25′ in the first box of section ‘3. who is
trevelling? ‘ then i made others remain as it was in the order
i mean i didn’t checked that i have ‘discovery 12-25 and did not put the registered numbers on it

then those price above showed

anyway i wonder if i do not have ‘discovery 12-25′
can i get discount price 65euros for this ticket if i identify myself
that im under 25( like passport, or school letter)? of i have pay in full of regular if i have not got it
(i ve heard if i have ‘discovery12-25′ that i can get 50% discounted price for tickets except when it’s full of reservation
or peaks.)
that 65euros just came out even i didn’t have ‘discovery 12-25′
so i really wondered.

and another question
my arrival of CDG Airport is 15:30 01/06 from tokyo
i worry that if i try to book it about 7hours before it’s departure
can i get ticket immediatly.
or if i have to make reservation for it
(what if it is gone i mean sold out)
but i ve got no credit card .. it must be payable by cash
can i make pre-reservation (pay it when i book it)?
if i can how ? tell me any solution that i can do please!!

Very Urgent for me to decide
please get me answer as soon as you get this
there is only 1 chance that i decide with
my agent next monday at 19o clock (noon in france)
and i should get this before that time please

thanks

if you loock at the rail europe site, you can see it all in english. There is also a 0870 number you can ring and book your ticket if your not sure, I did it last year myself, was very easy, they sent the ticket within a couple of days, good luck. the TGV site is awful, I had no end of problems with it.