I'm having trouble finding out what visa you can apply for. I looked at a Study visa but there does not seem to be one that would suit you. Then I looked at a Working Holiday Vias but from Thailand you need one of these qualifications Hold tertiary qualifications.
Tertiary qualifications include a:
• Doctoral degree;
• Masters degree;
• Graduate diploma;
• Graduate certificate;
• Bachelor degree;
• Associate degree;
• Advanced diploma;
• Diploma level qualifications.
Note: Tertiary qualifications do not include:
• Certificate IV;
• Certificate III;
• Certificate II;
• Certificate I;
• Senior Secondary Certificate of Education