According to Air New Zealand, pets on international flights MUST travel in the cargo hold - only domestic flights accept small pets as baggage
I appreciate your problem Shell, it's a difficult decision. Have you tried contacting a reputable pet carrier? They may be able to give you some advice and allay your fears a little. There's no doubt about it, an international long-haul flight is stressful for any animal, but with the right care they'll get through it. I honestly can't see you being able to take Ceilidh on the plane with you, whichever airline you fly with but I would love to be proved wrong.
This link takes you to a pdf file with info about carrying pets on planes with ANZ -
http://www.airnewzealand.co.uk/resou...t_passport.pdf (It's from the UK site but I would imagine it covers ANZ worldwide.)
Good luck.