I have been in China and have gotten 3+ years of experience teaching English here at Guangzhou Tech College.

I've been thinking a bit about a change of scenery, problem is before i left the UK i only got a weekend short course in TEFL. I am just wondering with 3 years experience is it still necessary to have a 'proper' TEFL - CELTA teaching certificate or is this overlooked for experience.

By the way i'm looking at maybe heading to somewhere like Japan, Hong Kong or Dubai.

Places like Japan and China you can still find plenty of schools (China more so) that do not require teaching certification. If you have a good reference you should be ok.

Dubai on the otherhand i have heard requirements are a bit stricter, although i have no first hand experience there.