Whereabouts are you from? Why do you want to be an instructor? Where do you want to teach?
I recommend you read this thread before thinking of a zero to hero course:
http://www.scubaboard.com/forums/ba...why-does-every-new-diver-want-instructor.html
If you still want to do this, there are loads of places in Thailand, but be warned - I've heard bad things. As you can see from the left-hand side of this post, I am from the UK. I dive all year, even when it is close to freezing. Every year my club has a trip to Malta, which is very popular with British divers as flights are cheap, the water is clear and there is plenty of sunshine. In 2011, there was a young Austrian DM working there. The dive centre we use take on DMs for the summer. They do not pay them but they will train them as instructors at the end of the season.
We stayed in touch via Facebook and saw he and one of the instructors spent Christmas in Thailand. When we returned last year, he came back to the same place to work as an instructor. On our first day, he picked us up in the minibus. One of the lads from my club asked him how he liked Thailand. He told us he loved the place but he was a bit disappointed with the training standards. They were backpacking with the intention of doing some freelance instructing. He said there are a lot of backpackers and gap-year students over there. None of them have much money but they all want to learn to dive; the dive schools need some money so a lot of the tuition is high-volume low-quality. The Austrian lad was quite upset about this; he has worked hard and he is a good diver - having to rush people through courses and sign people off before they were capable was an insult to his professionalism.
If you read post #169 of the link above, you will see what I understand of these 'cert factories'. If you want to go from zero to hero, I will not try to talk you out of it. Everybody began somewhere. What I will ask is that you consider your students. A diver should only teach others when he has reached a high standard and gained experience. Unfortunately, certain agencies will sell you all the pointless courses under the sun and push you into being a 'professional' before you are ready. It is unfair to teach somebody if you are not ready - you are ripping them off and compromising their safety.
I recommend that first of all, you just learn to dive, enjoy it, and gain some experience. Then think again whether you want to be an instructor. If you still do, do not limit yourself to clear blue seas and sunny weather. Have a think about Scapa Flow in Scotland - the water is cold (although in a drysuit this isn't a problem) but the diving is great and trade is good. The Germans scuttled a number of ships after the surrender at the end of WWI; many were salvaged but some are still down there. There are dive schools offering internships there. Not only is it excellent wreck diving, but it will set you up to dive anywhere in the world.