You don't necessarily have to go to a company in Liverpool NSW specialized in obtaining approvals and building permits, because the time in which the requests are issued is approximately the same. Information on the necessary documents can usually be found on the institution's website from which you wish to obtain the approval. You can sign up for a seminar on this topic supported by companies that provide consultancy in the field. Why seminar? Because there you can learn about all the aspects related to building construction.