it shouldnt really matter about the student number- its in case your booklet falls apart or something then they can retrieve your pages so its kinda a good idea. we do all that before reading time- we had about 10min to spare both times
that bad about the 45 min thing, we leave almost straight away cos there r just so many old ladies. i love them, they r so nice
also i got told not to touch the other boxes on the blue slip- i accidentely put a cross thru the bottom 2
if u wrote something wrong, your old lady should notice it and correct it so that markers wont get confused and your paper might be marked wrongly or they will look for papers that dont exist, or something