Welcome to the Bunnings Workshop community @HQ. It's fantastic to have you join us, and many thanks for your question.
Whether you need council approval would depend on what type of renovation you intend on completing, and I'd suggest that the best place to ask at would be your local council. As council requirements vary considerably around Australia, it's unlikely that there will be one rule for all councils. However, you might like to provide some details of the projects you had in mind and I trust our helpful members will contribute their own experiences around requirements.