As already mentioned you can change your name at the Births/Deaths and Marriages location in a city near you.
You do have to inform all other agencies of your change of name and address. When I mean address I mean Miss or MS,some organisations are not flexible and will send you mail addressed to Mr then you female name. A quick reply to them stating it is discriminatory to do so will hopefully change there minds.
No matter what you do with your transgendered life,you cannot change the age at which you may legally receive your superannuation. That is the maximum retirement age which is 65.(here in NSW that applies)
Further for those born in the UK or able to gain a UK citizenship,you can have your birth certificate changed to read female whether you have SRS or not. It requires the proof from a doctor or equivalent who is registered with the British Medical Board(i think) and advises them that you are TG. There are quite a few doctors practicing in Australia who have that endorsement. So,with a payment I beleive of $300 you can request a new birth certifcate from the UK births registry ,with your gender as female.
I am not sure of the other states in Australia but here in NSW you cannot change your birth certifcate if you were born here unless you have a letter from the surgeon who performed your SRS. And lets be honest here who needs to show a birth certifcate these days to get a loan or a drivers licence. 100 points of ID can be anything,not including a birth certificate. I changed my gender some time ago with the Motor registry without any ID.
Hugz
Monique