Whichever you choose, think about how you are going to allow northern light into the living/dining/kitchen area in winter. A roof or permanent shade will reduce northern light and make those areas cold and dark. If you live in a heating climate (where its cold for much of the year) such as Melbourne, Canberra or Hobart it would be wise to consider shading your outdoor area with something like a retractable pergola, a Vergola or similar, retractable awning, shade sails (that can be removed in winter), a steel pergola with a deciduous vine or a deciduous tree. Personally I think the smaller outdoor area is too small if you plan to use it to cook on a BBQ and entertain guests. Fine if you want to sit outside with the newspaper and a cuppa. It also depends on how you plan to use the garden. Veggie patch, kid’s play area, dog run, tinkering on a project, reading a book in a hammock, chicken coup, entertaining, something I haven’t thought of?

Hard to tell from pic if it’s metal ie vertical Matt colourbond or wood-ish ie James Hardie products like scyon, linea or axon. Could also be a batten over a plain cladding. For your purpose have a look at the James Hardie products.

Suggestions, turn the kitchen 90 degrees, have wall of cupboards between windows with oven and hot plate on that back wall. Island bench. The kids retreat just seems a thoroughfare to bedrooms. I would delete that area and the kids can retreat into the lounge room.

How about limestone ?