we're not talking about what you do or not. We're talking about what's required by the Thai government for a new or extansion of a WP. I live close to Bangkok Hospital CNX.... as long as I pay for it they do the works also but it's not required. Big difference.
Health certificate (simple doc consultation) yes. But bloodworks too? I've always getting the health certificate for over a decade but the bloodworks was only asked between 2009 and 2013.
Talk to your school where you are going to study. They will explain the whole procedure and provide you with the necessary documents. (Or were you planning on doing it the other way round maybe?) 😎
If it's Chiang Mai they are visiting I can only recommend Assist Thai Visa Services Group Co.,Ltd who also offer veru petsonal and cmfortable assistance including car with driver when visiting Immigration offices etc...