Oldchippy is right. you will need a permit and a registered builder and HOW insurance if over $16000. Yeah its a pain but that's life.
Your house value in Ringwood has gone through the roof in value so why are you crying poor. It makes sense spending 30-40K to improve your home and if you do it all legit you can sleep easy. One day when you are selling, pre purchase inspector will want to know about the permit, if you don't have it your asking price may take a hit.