Thanks everyone. Spoke to a Manager in Ethiad and he said train or bus will suffice- it seemed pretty certain, as the lady I spoke to before him said it as soon as I asked: "you need to get a train or bus ticket out." Unsure as to whether I'll play it safe and go get a visa tomorrow, or just book the bus. I've found some places where I could book a bus seat.

Yep..as they say in Thailand"Hup tu huw" .. I know what I would do..,and it does not hold you to fixed dates to cross out of Thailand. Have a great time...Cambodia..,.!

The ONLY alternative to this is to get a 60 day TV in your passport before you leave Ireland.
Not always correct now. I had to have a onward flight to get a visa. Other consulates may not be so picky.

Yep...a new one on me... Fined for overstay..no problem...apply and produce whatever in person for visa at consulate before entry, and pay fee..OK...don't bring gift or what maybe constructed as gift valued more than 10,000 baht in or may result in tax... What other gems in store...?

mcgardla, since you're only a week away from your trip it would be great if you'd take a few minutes after arrival to come back into this thread and let us know what you did in the end and how it all evolved. Such feedback helps us give more relevant responses to this oft-asked question.

QUOTE - "Thanks everyone. Spoke to a Manager in Ethiad and he said train or bus will suffice- it seemed pretty certain, as the lady I spoke to before him "
Onward ticket is supposed to be confirmed ticket , bus or train tickets are not confirmed tickets and not really practical to get from outside Thailand.

I've just booked one! thaiticketmajor.com- went through verified by visa and kasikorn bank as opposed to the site itself, so it is legit. There are a good few other- dodgier looking- websites that do the bangkok-siem reap route, but all in thai, so useless for me unfortunately but if can read it transport.co.th is the website for the government buses, selling the exact same tickets as thai ticket major. It's 793 Bhat for TTM, 750 (without booking fee) for Transport Co. So no major difference.
Again, I spoke to Ethiad and they said this was fine, but I've emailed them anyway just to have it in writing.
Success! .....So far

#14 bangkokboy I definitely will do that! I will keep in touch as to what happens with Ethiad in Dublin and the getting through immigration in Bangkok. The people I'm travelling with will be going through Heathrow, so I'll let you know that also- just to see what differences there are, if any. Thanks!

I wouldnt worry about reporting on Immigration in Bangkok. As we've all said, fat chance of anything happening.

If it's Etihad both ex-Dublin and ex-Heathrow then you'd expect the same requirements at check-in (but not necessarily). If different airlines then it's anybody's guess - it really IS down to the airline in the way they interpret the rules. Telling them at check-in (if asked) that the office said a bus ticket would be fine, when they want to see an airline ticket...........well, wait and see. Ah, but you'll have your email!
As for arrival Bangkok, as westwood and the rest of us have said, there'll be absolutely nothing to report - we know already that you will not have any problem.
BTW, what's the price diff between the bus ticket and the cost of a 60-day Travel Visa?