ok brilliant. thanks very much for your help guys! :)

ok thanks guys! my main concern was that i was now on overstay and would get banned from returning :( so if i leave the country, could I apply for the new non-B visa at the Thai embassy straight away, or would I need to buy a tourist visa first?

I was advised that this was the easiest way to do it - I still have my work permit with me, but my previous employer submitted a letter of resignation stating the 25th April and told me i had to leave the country on this day, get a tourist visa, and then apply for a new non-B visa after that... i never got a receipt of my work permit being cancelled :S

Here's the stamp