If anyone is travelling on Etihad I have received the following email response:
"The power supply on the B777 and Airbus is the same type. It will accept the North American Standard two or three prongs, or the European two prong connector. The voltage is 110V @ 60Hz (standard US domestic)."
So it looks as though they have covered off most options, other than I will need adaptor to use my UK plug.