just to add my view on this,
just bear in mind, i am not a cadet with SIA, but i do have a friend there.
u r given 15 hrs in singapore, and a further (upto) 21 hrs in perth. if u have it in you, that is more than enough hours to clear your first solo. most of my friends (who are in major airlines all over the world) have cleared first solos in 6-15 hours. not bragging, but if i can fly, think most ppl can
cheers,
otr