They have your biometric data, fingerprints with ur Aussie passports, if u try to come with ur UK passport so ur Aussie passport show up... Don't know if it's good but i can believe not.
U need to make a passport for the car at transportation department, at the border u need to make a insurance, and as i remember u need 3 sets of copies, passport, passport from car and so on. The passport need like 2-3 days and is valid as long your toad tax.
then let us know the cost, how much the agency charge. I did it once, this agency charge for retirement 15k and for marriage 35k, because they can't do it here, they will take your passport to another state, not remember which it was, if you below 50, there is no retirement option.
its a marriaged based visa, not a retirement, the cost are 30-35k, a marriage visa is one month under consideration and the next higher immigration check the staus plus interview neighbors, so please not spread misinformation. U can call your agency and tell us the price, for a non o based on marriage without 400k in the bank 😎