Driving lisence in Thailand

This may be too late to help, if at all, but here go's.
To start with you need a visa other than a tourist one to gain a Thai D/L
Holding a tourist visa will allow you to hire and drive in Thailand, providing you hold an international license…… official line! Unofficially nobody really cares what you hold…… until you have an accident, and then it's going to cost you, maybe just money, maybe more!
To get a Thai D/L you need a non immigrant visa, i.e.: retirement and student. And then you can not only apply for a Thai D/L. The fact is you are now no longer classed as a tourist, and as such you are required to hold a Thai D/L, and again if you're involved in an accident and hold a non immigrant visa with an international license, you could get off light by making a donation to the boys in brown!
The Thai system is set up to issue foreigners with licenses, if you meet the requirements, problem is you wanting a license is a pain in the ass for them to do, so! Unless you know and can communicate what you want and demonstrate you know your entitlement, you may just get blown off, as this is easier for them to do.
Note, license issue is not centralized as it is in western countries. Find your local licensing office; be prepared to wait all day if busy, if not, along with helpful staff you could be in and out in an hour,

However, saying all that, you are from Rayong, it shouldn't be to hard to get it done down there, you can expect two licenses, one for motorbike and one for car, first issue, normally one year the next one, (renewal) 5 years.

You may also be required to take some form of tests, not driving, when I got my license I had to take a depth perception, and reaction time test…….Ha ha. I felt as though I was trying out for the royal flying core, class of 1914. 

Hope this helps.

I'm not sure if you can do it via the mail now, but you can get your International driver's license via AAA. Their website looks kind of not-legit, but it is. Hope this helps! http://www.aaa.com/vacation/idpf.html