I have a non-immigrant B visa.

I will be in Bangkok soon to hand-in my application for my work permit through my local office in Bangkok. Do I need to leave Bangkok and return once it is approved?

Thanks

What is your question? Why should you leave Bangkok? The visa allows you to stay, the WP to work.

What is your question? Why should you leave Bangkok? The visa allows you to stay, the WP to work.

The visa allows you to stay, but as long as the work permit is not approved, can I work?

No, unless it is absolutly necesarry. But that is more in cases as machines needing repair and the repair man has to come from abroad and there is no time to apply for the WP first.

When applying for work permit, will the dept of labour approve the work permit if the applicant does not have a paper qualification, but with years of relevant experience? Will a letter from the company be required to attest to this?

"paper qualification", this is not needed.