From the post I have read, I can
gather that you've just finished your poly maybe last year and
you're currently working part-time while waiting for
enlistment.
Let's see, you're too old to defer your
NS, so first serve your NS. DO NOT
AWOL or do silly stuff and go DB. If you're really interested in nursing, dun be
afraid to go ask around about the courses or ask a nurse how its
like.
The fastest you can defer is only after
2 years of NS, of which you can apply for early distruption to
study.
During your 2 years in NS, you should do
your research and find out which course you want to take. If you
have no money, you can try looking around for a scholarship. Or
look for grants. ALSO, you're not allowed to work even part time
when you're in NS(if you do, just be careful), its against the
rules unless you seek permission of which Mindef will only seek on
a case-to-case basis.
All this is hard work, up to you, whether you want to work hard and
achieve your dream!
Good luck! 
