Not just perfect, the weight isn’t distributed to the external...

Not just perfect, the weight isn’t distributed to the external walls so you need more concrete and most likely a different slab classification, most likely P, that will cost a fair bit more.

Still going to have to go through the potential cost of face brick or render, then the root around for the fixing carpenter who will choose to work on a timber frame over block work so they will want more money.

Getting window and door frame openings will still be a challenge, I understand where you’re coming from but when they’re installed prior the brickwork is hard up, you’ll have to have a frame for tolerance which is possible, probably not desirable but a reasonable question Timboc, you’ll essentially have to run a trim if you wanted timber windows.