Thanks for all the comments.

We are freehold and building well within the boundaries. The first quote includes all consenting and from talking with the council we should have no issues there.

The roof will be a 3inch thermopanel variant of one type or another. Solid with no glass. I hope @graemeh and @froob are correct as we hadn't counted on lawyers fees in our grand budget.

KennyM, welcome to Chch prices! The cost of doing anything, from building a simple fence to electrics inside has increased since 2011. According to the DBH we are now more expensive to build per sq metre than Auckland by a bit of a margin and the most expensive town/city in the country. For the consented build we require soil testing and an engineers report to get consent.