OK. I rang ACERT - the phone number you listed is the fax actually - real phone number is 07) 32563077
1) see a draftsman / architect to get plans drawn up
2) the drafstman will have a good idea of whether or not you will need town planning approval
3) if necessary (cross fingers that its' not) town planning approval may take many weeks and add $5K to process.. yuk.
4) lastly - submit draftsman's plans with engineers approval to Certifier. They will issue Council approval and building approval.
Does this sound correct?