PHSE = personal, social, and health education ?
If so, according to their website, I'm sure it's taught. As for LGBGT, this is Thailand and it's a very diverse culture. Perhaps you'd be better off looking for a school in the deep south of the USA or a Muslim state?
https://www.hastin.ac.th/approach
Our 9 Key Areas of Development:
Personal-Emotion Development
Social Development
Physical Development
Language for Communication Development
Literacy
Cognitive Development
Knowledge and Understanding Development
Problem Solving, Reasoning, and Numeracy
Creative Development