Hi Mr NewZealand
I found a shipping record dated 22 August 1908 for George H Wood (Single, Carpenter) and John H Wood (Single, Carpenter) who travelled 3rd Class together on ticket #276, they sailed on the vessel "Athenic", travelling from Plymouth to Wellington New Zealand.
The ages of these two is not noted on the transcription.
Could this possibly be the 2 brothers?
As you say George Wood does not appear on the 1911 Census, and I noted that John Wood does not either, which would fit in with their 1908 departure.
On the New Zealand BDM Historical Website (which is accessed through the Department of Internal Affairs website) there is a death in New Zealand (record does not state where in NZ though) of George Henry Wood in 1951 aged 77 years. The record would need to be purchased for more information) (Ref # is 1951/23996)
You could Direct Message me for the Website link if you like, not sure if I can post it on here.
This age fits perfectly with your George Henry Wood who was born in 1874.
Henry Wood was still in Guernsey in 1911 with his wife Helen and 3 children, Ralph (5), Edna (4) and Edith (2). He was described as a Managing Clerk of a Fruit Growers.
I found a shipping record on 23 December 1920 for a Henry Wood who left Southampton for Auckland New Zealand. He was born in 1879, was aged 41 and described as Retired. There were no family members travelling with him however. The Vessel was the "Rimutaka" and he travelled 2nd Class
A year later on 10 November 1921, Helen Wood and her children Ralph H Wood, Edna L Wood, Edith N Wood, Muriel R Wood and Phyllis J Wood left Southampton for Wellington New Zealand on the Vessel "Ruahine". They also travelled 2nd Class. Their former Guernsey address had been given as "Le Vauquiedor" St Andrews, Guernsey"
Younger brother Clifford Wood was single and living with his parents Thomas and Elizabeth Wood at the time of this Census.
The 1911 Census states that Thomas and Elizabeth Wood had 9 children of which 4 had died by the time of the Census and 5 were still living (living being George, Annie, Henry, John and Clifford I am assuming).
Annie Eliza Wood was working as a Companion/HouseKeeper for Mrs O Halloran at the time of the 1911 Census. She was still single.
Clifford left for Wellington New Zealand on 13 September 1912 on board the "Tainui", he was single and a Clerk. He travelled 3rd Class.
I searched for information on Lillian Wood but did not find anything past the 1901 Census. As Thomas and Elizabeth Wood are quoted as having 5 surviving children, it would appear that Lillian died between the 1901 and 1911 Census, unless John Wood died after 1908 and prior to 1911??
Hope this helps.