We did engage a town planner and the whole experience was expensive but educational.
There are limits to what you will or will not be able to do depending on the zoning of your area.
What we did learn with the help of our town planner is that we can just plan for a pre-lodgement meeting with the council to understand the concerns and address these issues. And if your proposed DA is not feasible, you don’t need to waste your money.
We have two drewlings on our property and can comply as a BNB, and our planner helped us with our response letter. I hope this helps other anxious hosts.
If you got a letter, chances re your neighbours complained. So I also recommend speaking to your neighbours and changing your operation so their concerns are addressed. The key change we put in place was to request that our guests speak inside the house after hour so their voice don’t travel to our neighbours at night. That works well.