based on the accurate dimensions the most economical update would be to replace the spa with a shower over bath, keep the existing vanity and toilet, reuse existing taps and retile but, any bath renovation is always much more expensive than imagined, and the unexpected expenses (eg asbestos under tiles) can add up and a minimum of ten thousand for a very modest upgrade wouldn't be surprising...If the bathroom is in acceptable condition especially if there's any possibility of a future expansion towards the backyard that could affect the current position of bathroom and laundry) i suggest (subject to confirmation from a plumber) that you consider reorganising the other spaces and sacrifice the wiw to create an ensuite with linen storage taken off the middle bedroom..surprisingly an extra bathroom could be less expensive than renovating the old one but i would still allow at least $10,000 with careful planning

Few things 1. Still not enough space in the store for a bathrub. 2. I will loose the storage space, storage is very important with growing kids, this way i will have a nice big store room to store. 3. Cost and risk - to run drain i need to cut a lot of concrete and you dont know if there are beams underneath, cutting the concrete slab all the way to store is like cutting the the house by half. There is same risk involved when i remove that single brick wall for the new bathroom,. but i am planning to do another wall first then remove this. 4. Upstairs bathroom is big enough to accommodate all - its a 2030 x 3600 in size 5. The hot and cold water coming behind the wall(bedroom1) where i put the new bathrooms, so just need to drill it through the brick. I know either way i have to cut a lot, one is to cut the concrete slab, other is to remove a brick wall. I thought about putting one outside, but then i have to involve a surveyor, council etc. to much time consuming that way.

Thanks and sorry for not providing that information. This is a new room ensuite, not a renovation. So there is some flexibility in the window placement. On the wall facing the sliding door the single window is 1m wide x 1.3m high and is 1.5m off the ground. On the wall with two windows the windows are 1m wide x 0.5 and they are 2m off the ground. The floor will be tiled. Many thanks!

thanks siriuskey, have attached more of a floor plan. i am leaning towards (hubby needs convincing) putting bath in master en-suite (new addition) as the bathroom we are renovating would be more of a powder room or bathroom to service the study if that was ever changed into a bedroom. As you can see the guest bedroom has an en-suite off it and 2 other bedrooms in another section are serviced by a bathroom. Ceiling is currently at 2700mm all round, no sloped walls Don’t know why it puts my photos upside down 😩😩😩