Find Ancestors

Hi, My father was married before he met my mother. On his Service papers for the Navy which he joined in Brisbane, it says his wife was M. H. Brown. address 6 Wellington St. Croydon.
I don't know which Croydon, but I always thought he was married on This side of Victorian border or just over the border of N.S.W. but I could be wrong and it was in Queensland.
Now as the story goes. his marriage was annulled, after the birth of a daughter Susan, by the father-in -law. But this could just be a story.
I would like to find my half sister if it is at all possible. Obviously he must have been married before 1951 16 April as her name was on his enlistment as next of kin.

Please, please if any one knows where to start to look this up could you help, it would be greatly appreciated.

Debbie wife of Willy

tree on anestry has hector being born in England, so maybe this is him coming to Oz, look in Queensland for a marriage

Name: Hector J BROWN
Date of departure: 27 April 1949
Port of departure: London
Passenger destination port: Brisbane, Australia
Passenger destination: Brisbane, Australia
Date of Birth: 1932 (calculated from age)
Age: 17
Marital status:
Sex: Male
Occupation: Labourer
Ship:
Official Number:
Master's name:
Steamship Line:
Where bound:
Square feet:
Registered tonnage:
Passengers on voyage:

MOOLTAN
79866
Captain C H Baxter
P. & O.
Brisbane, Australia
20952
1056

Thanyou again Victoria, you are a great help.
Debbie