The room itself is galley style with the Outside door at one end and and the Internal door at the other end. Both doors open inwards to the room. The internal door is hung on the left and the external door on the right (vice versa if I'm looking from the opposite direction). Anyway, I have found the answer to my question, which is - that it doesn't matter. I appreciate everyone's comments. Cheers

consider Colorbond steel fencing panels, the same profile as the fence and similar colour to the pool house, easy to cut and install using gate fixings and readily available at Hardware and fence suppliers but try full height vertical doors of the half lift up door

Love your story, siriuskey! Dogs are such characters. My daughter is renting a house with vinyl flooring that resembles floorboards. She has a big dog so uses area rugs and carpet runners to minimise scratches. He was traumatised somehow as a wee pup and won’t let her or anyone else trim his nails. He would have to be sedated, as in knocked out cold. She can’t be doing that, so walks him along concrete footpaths to keep them somewhat in check. Despite her best efforts, his extra large paws have scratched the vinyl a bit. I agree with others that tiles, polished concrete or other concrete-type finish floors will withstand any punishment a dog can throw at them. Area rugs and runners are good idea in dog-traffic areas so they don’t slip and damage their joints.

what is the size of the gap between door and door frame? We have a waterproofing system on our wooden doors. Two parts: First is the the metal attachment to the frame, this is about 1cm in height. Second is the metal and rubber attachment to the door, this is about 4cm. So the waterproofing install is about 5cm in total. I have attached photos for reference.