Do you have to use the smaller front boundary for the garage? Is the noisy living space going to work with all bedrooms coming off this space? If the garage went to the south and can it be on the boundary in Sydney, that would leave the middle for bedrooms and the northern aspect for living, as most Australian houses benefit from northern light. The front setbacks would make an ideal outdoor space which high fences or high shrubs if not allowed high fences, if on a busy road most councils allow you to have sound barriers, leaving the entry to the house to come in off the long boundary, which you can make more of a feature. You have a corner block which is always a bonus. The beds will then have a quite zone, the living can have that northern end and cars can be pushed to boundary. Always look at the site before you look at plans. Always make sure the living aspect overrides the plans. Always make sure that living in a space overrides the plans, always.

realising that you did not mean to have one long narrow room but i think we all recommend an L shaped extension (not necessarily my suggested plan) because it will be much more cost effective than removing the whole back wall of the house and replacing all the separate ceilings and windows and not achieving much more than an enlarged bathroom, bedroom and small ensuite..the Lshape extension of similar sq m would create a more comfortable floorplan for the whole house with a simpler extension that also has the potential for a deck or alfesco to enjoy the bush view..photos of the roof and back of the house and measurements of the distance to the side and back fences and location of the pipes you mentioned and rough measurements of the bathroom, laundry, wardrobes and short hallways would allow a much more detailed floorplan to help invite more suggestions

This floor plan has a single garage, with bedrooms grouped together at the front of the house, the Music Room has been moved to the rear away from the bedrooms as it would make too much noise for those sleeping. It can now be opened up to the family kitchen dining, courtyard and Alfresco and can be used as a play room(/ guest room) giving children great indoor out door play area in view of parents. There's a study with a similar view. A powder room closer to the rear of the house for easy access, The main bathroom is done Japanese style. The master suite has the WIR between the bed and the ensuite, no noise etc when in use to disturb anyone. I have made the passage way extra wide and more like a room which has a linen cupboard, you could certainly make this narrower and add to the bedrooms if you wished, This comes to 204.5 sq m. cheers

Am so pleased for you, Lucy. What a lovely home and it very much suits its gorgeous setting. Love, love, love the use of timber, and all that glorious light. I now also have a serious case of dining chair envy. And the view! No wonder you’re (rightly) pleased. Health, happiness and many, many years enjoying the fruits of all your hard work to you and yours And to all the lovely Houzz community members who helped Lucy, and myself, cheers you wonderful people