I would strongly recommend you steer clear of the Singaporean MOE for work or training. While we all hear a lot about how great the school system is, fact of the matter is, very few local teachers are hired by
International Schools as the methods/pedagogy are so different. (Having said that, I do know some wonderful local teachers, so it's not fair to tar them all with the same brush...) Anyay, you really do not want to end up in a bond working for the MOE.
There are several offshore teacher training programmes that can be completed in Singapore. I'm pretty sure the open poltech in the UK has a PGCE that can be done by distance. I know Australia has several (Charles Sturt University is one). Also there are several US colleges that will allow you to study from another country. You can do your practicums at
International Schools. I know a couple of people who have done this.
I'd say your first point to consider is where you want to teach, then look at getting a qualification and license that will allow you to teach there.