So I'm changing jobs.

Are these the steps to getting my next non-imm B extention??

They're going to cancel my WP here on the 30th of April, which cancels my non-imm B.

I need to go to immigration before this to get a 7 day 'bridging' visa from the date my WP is cancelled to the date I go back there with a new WP to extend my non-imm B.

I go back to an immigration office within the 7 days, with my WP and extend my non-imm B. Without the 7 day visa, or getting the new WP within the 7 days means I will lose my non-imm B and then have to go through the process of getting a new one in another country.

Is this correct??? Does anybody know?

You will lose the visa on exit but in some cases you can obtain a change of visa as part of an extension process inside Thailand if you meet the requirements. But in most cases it is probably just as easy to obtain a new non immigrant B visa from a Consulate once work permit receipt is obtained.

Ok, but I (hopefully)won't be leaving the country as I'm working here now and have my contract signed for next job with a different company, unless there's a delay with the WP, or I don't get the bridging visa, or there's some other complication.

I think the above steps are the way to do it.

Cheers.