Hi Anita, welcome to the forum,
tickets generally go on sale the 1st weekend in october but that isn't deffinate. Usually there are options to pay the whole amount or a 50 pound deposit on the day and the balance payable by end of feb.
if you keep coming back to this forum any questions will be answered and if you are on twitter then follow glastowatch. you will get to know the ticket sale date through him, here or the official website.
some people have problems getting tickets and its not guaranteed but there is another ticket sale in april so you do get 2 chances.
good luck and look forward to getting to know you through the forum, we are a nice bunch