Altruistic surrogacy is legal in all of Australia and open to same-sex couples according to the Assisted Reproductive Treatment Act, 2008 (ART) (copy of ART on the website). You will need to find a surrogate, to actually carry the fetus, as well as an egg donor. Australian law requires that the egg may not come from the surrogate. The sperm donor may be you or your partner, or through an outside sperm donor.
After the baby is born, you will not automatically be recognised as the child’s parents. According to the law, the surrogate is the child’s mother. You and your partner will need to apply to the county or Supreme court for “substitute parenting orders”.