I think the woodland grey for the main walls would be perfect, to recede it and also to match in with the trim on your house. I suggest doing all other trim in white, including the door, to keep to simple and clean looking.

Hi James, Some time ago I also faced such an issue. I've gathered some information, thought everything out and applied to one of the Melbourne companies and I'm too happy to meet them .They provided me with a shed design that to perfectly suits me. What I needed was just tell them the size and they delivered a shed of the size I wanted. So, if you want a durable shed, I can give you a link to their site.

having used steel for numerous buildings including an A1 steel building for a small holiday shack built on a rural block i have to say that you need to understand that although the steel kit is economical all the other trades are the same as building any new home although erecting the frame is faster but you may also have to think about off grid power, phone, a sewerage system, water supply, fencing and roadworks but the site plan and building design will be the most important consideration and recommend that you check yourhome.gov to make the best of passive solar design but is it it a house block or acreage, do you have water, phone and power and how many will live in the house?

Is it easy to remove the roofing and replace it again? If you are prepared to do that I would recommend using Anticon insulation under the roofing. It is a foil faced fibreglass blanket (foil down) that you place tightly over the battens before you replace the roofing. This will stop the condensation and make it more bearable in summer. You can get it in various thicknesses but most typically R1.3 to R2 (60-90mm). It needs to sit tightly to the underside of the roofing to prevent condensation. It gets squashed over the battens, but that doesn't matter so much. When building from scratch it would be better to place it under the battens for more consistent insulation thickness. I always use this under metal roofing, even when there will be ceiling insulation as well.