Active job

We want our bathroom done up but don't know where to start

We have a bathroom and laundry next to eachother. We want to knock out the wall between and create a shared bathroom/laundry, using the current back door porch area as the laundry and opening up the bathroom. Will need appropriate ventilation and lighting. We have relatively new toilet and vanity that can be reused, but want seperate bath and shower. The current flooring is damp and will likely need replacing. Preferably with tiled floor. Unsure where to start! Need ideas on how we can progress and how much it is likely to cost! How to get the paperwork together and approved by council etc.