The answer to your question depends on whether you intend to pursue schooling in the private or public education sector in Singapore. If you were age 17, that would put you in Pre-University 2 in the Singaporean public school sector - new students are not admitted at this level in Singapore public school. International schools following different curricula (eg British, American, IB) may have different policies, though. In the case of international or other independent schools, each would likely have their own system of scholarships (if any) and I imagine these would be extremely competitive. To find out more, you would have to contact various schools directly. For a list of recommended schools, have a look at our International Schools in Singapore page.
You would also need to apply for a particular visa called the Student's Pass to be able to live and study legally in Singapore. Would you have the means to pay for your own apartment, food, and other expenses while living in Singapore? If so, you would need to be able to prove this to the Singapore department of immigration in order to be considered for a Student's Pass. You can learn more about this on the Singapore immigration authority's website (click here to read their page on Student's Passes).
What country are you living in currently? It can be very difficult to adjust to a new curriculum, especially so late in your academic career, so it may be worthwhile to aim for a school in Singapore that has the same curriculum.