We have a similar home in a sydney beach suburb. We are in a different position where we have bought ours as a downsized but are just about to restore the old 50s beauty to its former self. We have quotes of around $400000 to gut and change the floor plan which includes 2 bathrooms and a new kitchen and also add internal stairs to the garage and a large deck off the back, lift some ceilings and replace gutters, eaves ect ect ect. Attached are my inspiration boards and what the house looks like now, hopefully in about 4 months I can update you.

Gal will go grey (mid to dark grey) over 12 - 18 months. Initially VERY bright. The energy absorbed changes accordingly, from sub 5% absorbed to ~35%. Zinc maintains brightness for longer, though still suffers some dulling. Say 5% to 15% over time. This can be avoided by coating with a product called 'Sharkhide' metal protectant, used to stop aluminium boats oxidising. For there reasons many councils will not allow zinc or gal roofing (visual amenity, reflection issues), while making the houses more prone to requiring summer aircon at the same time. Surfmist Colorbond starts around 9% absorbed. If purely for energy reasons, a light colour might be the only option. If going dark, I would suggest at least doing the 'less aesthetically important' sides and rear in a light colour. Your call. If you go all dark, ensure you have good roof space ventilation for the summer that can be closed in the winter, and lots of well installed ceiling level insulation. Spray foam is more reliable over time than batts, see Spray It Solutions or similar (they have the Formaldahyde free Canadian Icenene foam).

Rather than changing the look of your already great looking home, focus on maintenance rather than aesthetic 'improvements'. Too many 'modernise/improve/change exist. style' rather than spending the money on actually fixing their home. As Dr. has said, sort the asbestos. No tradesman will work on the dwelling until they have removed asbestos from where they're going to work, even if its just those few affected walls, it'll be removed and require re-cladding. You could use Fibre Cement (Hardie) sheet with the battens again, then as budget recovers complete the asbestos removal. I like the existing batten and sheet cladding. It'll look awesome once completed and freshly painted, new landscaping, etc.

Thanks for the advice team. So the house is block work on a cement slab, but when we did our renovating in the bathroom and had to cut through and re-lay the floor in the very small bathroom we noticed that the slab was incredibly thin and had no reinforcing. The walls have some cracks however we did have the building inspected when we bought it and thought we had a solid shell to start with. (Its brick and cement we said - what can go wrong?!) Our house is not in the flood zone. There is an asbestos ceiling which has also complicated matters a little - everyone who has quoted on the job has vowed not to disturb it - but I am not sure when you are walking around up there and pulling the original roof off if this is actually possible. The roof is a flat cliplock roof with no crawl space at all, so the ceiling is on battens that are attached to the rafters. The block of land is 822 sqm and will be worth about $130 000 if the house was demolished. (Demolition is set to cost around $30 000- due to asbestos etc) We have spoken to an architect who has told us that it may be possible to reuse our kitchen, the solar set up and some windows, but if we try to force the project to reuse all of our windows and doors it could end up being counter productive. So if it happens to fit we might reuse. I just spoke to a real estate who are telling me that in our area a small new house (3 bedroom) will not reach the $300 000 value point - so it may be impossible to reach the right formula to allow the bank to lend for a rebuild-