In my last house, after adding a living room (the area you see this side of the arch) and also updating bathroom etc I couldn't afford to reline the ancient walls in my little lounge (when I removed the purple wallpaper I found a mixmax of boards, gib, pinex, plywood and holes!) so I plastered walls all over with layers and layers of newspaper and wallpaper paste (papier mache), then after applying primer/undercoat I painted with 2 similar colours (rich reds in this case), and stippled the surface with a plastic bag. This made it look just very slightly textured like leather and successfully disguised the uneven surfaces. Gallons of gap filler filled the gaps between the old T&G ceiling boards and evened out the mismatched skirting and scotia. Again white paint on all the trims. Amazing what can be done when you have to make do! This was a great cosy little room! (Before photo is the 3rd one)

Located this company https://4ddoors.com.au/product/side-sliding-sectional Garage doors that open sideways.

This wasn't your question, but looking at a possible boxed out window in the open plan kitchen dining living it shows just how limited you space is. The following 3D overview shows a boxed out window seat. I have run the kitchen along the same wall as the new window, The Island is 2m x 900 with 1m between the wall base cabinets and the island and 1m between the Island and the wall where your plan shows cabinets. If you have/had cabinets along the other wall as shown on your floor plan they will be 600 deep this would make the island 1400 x 900 which is small. Has your kitchen been renovated and were you considering that, if not. Looking at the overall size of your open plan area I would be considering 1 or 2 large stacker doors to open up to the rear alfresco, that's what I would do but you need to choose what will work for you PS I think that the boxed out window at the front of the house is a lovely idea but possibly not right when it faces West.

Orange . That's all you need . A mid orange on the gutters , that pinky timber gable , and the garage door , and also re-do the reddish burgundyish stripes on the awnings in that mid orange . Summer , beach , the bricks are nice , the roof is nice , the trim isn't and neither are the awnings . I did wonder about doing the window frames in a charcoal , but i think that is too modern and not enough beach for the era and theme of the house , and will almost look like black eyes . Just a simple , honest upgrade and update is all that is needed .