thanks everyone for your info.
I think from what Canadaguy has said even though I got a second shot 4 years later I should still be ok and be almost fully protected for a good few years yet so that's great as it saves me having to mess around in Bangkok to get the shot.. especially as I will be short on time with the new 15 day rule!!
Thanks again for all your help.. sounds like both sides of the world need to get the same story to avoid confusion!!