URGENT advice required

If you're travelling anywhere in the world on a Tourist Visa the immigrations authorities anywhere will surely want to see a return ticket which is dated for sometime in the period of an unextended visa stay in their country. You should always have a return ticket for this and other reasons, such as flights being considerably cheaper when you buy a round-trip ticket as opposed to one way fares.

Your ticket should be one that allows you to change date on the return without charge or with a small additional surcharge. That will also help cover your butt if things don't go exactly as planned with the company.

Cheers,
William James Woodward - Brazil Animator, Expat-blog Team

The real issue is with the airlines that is providing your flight into any country. For if they allow you to board an aircraft which you are not in compliance with the receiving countries visa rules the airlines must provide the transportation to get you out of the country. So the easiest way to make sure you have got the proper paperwork, be it visas's return flight required etc, is to check with your airlines. Their off the cuff answer is often that you need a return ticket. But ask them to check the specific country (They have it on their computer). Hope this helps.

WJ,
  It does not always follow that all countries will require a RT ticket or exit out of their country. I just left Mexico after living there for 6  months...no such requirement. I now live in Vietnam...no such requirement if you come with a tourist visa already in hand. However, if you get a visa on arrival in Vietnam they want to see an exit ticket. And I could provide many more countries with no such rule.

Follow what wjwoodward has stated. 

Buy a 12 month return ticket. Full fare and the ability to change flight dates within the time that the ticket is valid for. 

At some time or another you may have to leave the country.

A lot of people coming here simple buy a airplane ticket from Bangkok to XXXX for a few baht, that have it travel date inside the time of there Visa, That way they have no problems at the Airport back home and in Bangkok Airport...

My self i never be ask to show return ticket and same same for my friends down here, Maybe it is diffident from country to country...

As the man at the Thai Consulate back home told me, buy a single ticket, and IF you stop and ask about a ticket out of Thailand, simple buy it in the Airport or online if you have internet, Bangkok to Laos or other country for a few baht...
Same if they stop you in Bangkok and ask...

What visa are you arriving on? I ask because you say you hope to secure work after your arrival and that your employer will secure your visa.

How will he do that after you arrive given that visa's are obtained outside Thailand or you get a visa exempt stamp at the airport.

BTW in my numberous visits to Thailand over the years I have never been asked to produce evidence of a return flight ticket, just lucky I guess

The thetfeldon is correct when he states"he has never been sked for a return ticket flying into Thailand" This is the case when you have a country that has a "Visa on Arrival" policy. The same for Vietnam. And if look at it terms of airline liability the airline is always off the hook if they transport someone to a country that has a VOA policy. The problem arises when the when the airline does not check your paperwork with the requirements of the receiving country and allow you to board. If you then get to a country that requires a visa in hand, that country will refuse you entry. It then is the responsibility of the airlines to fly you back to your origin. Mexico is yet another country, as are many in Central and South America that have VOA policies. In this part of the world the PI and Singapore are other examples. There are oodles of them. In these countries an exit flight will not be required.

Thanks for your responses. Job and visa-wise, things are all in hand.
I now have an open ticket and leave from Heathrow in ten days. I'd still be most grateful for any suggestions as to what I should bring with me