Can anyone give me any advice please??

I am a UK citizen who came to Thailand earlier in the year as a tourist. I was issued a standard tourist visa on arrival (30 days i think). Whilst in Thailand I became friends with a British girl who was teaching English in a local school, and with permission from the school I spent some time helping out in classes, helping the children with their pronunciation. This work was voluntary. I recieved no payment and did it just to help out and for my own enjoyment. I returned to the UK at the end of my trip within the visa period with no problems. I have now been offered a job as a teaching assisstant in the UK and my future employer is unsure as to whether I require a Certificate of Good Conduct for my time spent in the Thai school.

As I wasn't in the country on a temporary resident or working visa do I need the certificate???, as I did the work as a tourist just helping out for a couple of weeks??

Any advice would be great, thank you.

^ I doubt it, as you were only at the school for a few days. You'll need a CRB check for the school in Britain though.