Removing the walls will connect the spaces and work quite nicely. I like the way it leaves you will functional wall but connects the spaces. As an Energy Rater I would advise against removing the doors to the stairwell though, and if needed add a door to the kitchen/stairwell. If you can mange to keep both spaces separate you will effectively trap any heating and cooling in the new living/kitchen space. Heat rises naturally and if you leave an opening to the stairwell that is where your heating will go.

the stairwell is going down, not up. living/dining is the upstair floor, as its a split design all the bedrooms are down stairs, but both level has floor level access due to the slop in the land.

area of dining/kitchen is 42m2, living 24m2, so total 66m2. not easy to heat with all the glass doors and windows.

Yes the larger the space the more it costs to heat it. But good curtains, pelmets and even ceiling fans can help. Be sure your entry doors have weather seals and seek advice from an experience supplier when choosing the heater. Some heaters will put out more M/J than others so it is worth getting it sized to the room. And ceiling insulation is a must.

I’ve been looking at opening up my dining area and are pretty keen on full height cavity sliders.
Is there space in your wall to have 2 sliders tucked away so that you have the option of closing?

This is what I mean

brick wall so no option for cavity sliders

gas heaters are already in that middle wall as marked, old heaters i think i need to service them as not sure when its serviced last

also has two split aircons on both rooms on the far end

no weather seals on entry doors, i can feel cold air is coming under some doors, where can i get the seals or is there someone who can come nd check all doors/windows and seal them

tin flat room with not much space in between. I think there is insulation in the middle if not its very hard to do anything without opening up the roof sheets.

We have double roller blinds on one side. No curtains on patio door(kitchen).

Try this for door:
https://www.ecomaster.com.au/dd/

Not sure where you are, but this company does assessments also (they are in Melbourne)

Personally I like separate rooms. For the same reasons you have mentioned, much quieter and easier to only heat/cool the space you are using.

Just a thought You seem to have a decent balcony what about French doors or by fold being put in to open up both dining and lounge Do you have a view Concerned if going to eventually selling removing walls etc maybe overcapitalising Weigh up cost against percentage of value

at least look at putting in glass pivot doors

I agree with Westland about keeping the doors to the stairwell and opening up lounge dining area.

the balcony side is full of glass windows with two glass doors, so the view is good. if i gut open the wall the width(720mm) probably wont be enough to have a pivot door.

Hi, I’ve been having another look and note you have a kids theatre room at back to contain some noise. Opening the living to the dining would be better for entertaining, and as I said look lovely.
Not sure what furniture placement you have in lounge, but would you consider moving the doorway to the stairway down to opposite corridor into study. That might then allow you to keep doors on that entry

yes planning to do a theatre in the back room.

currently we have an L shape couch but thinking of changing that too for something not that bulky, may be like a 3+2+1 or a 3+snuggle+something.

too much work and mess to move the doorway, its a brick house, all the walls are brick either single of double.