For chair scoot and sit space, I'd follow the guidelines for a rug - 4' all around. Then you want to be able to navigate around the table while people are seated, so add another 18" all around. Are you locating the table at the end of the galley? Maybe you could use a banquette on one side or in the corner https://www.houzz.com/photos/3rd-street-bungalow-traditional-kitchen-austin-phvw-vp~214425

Not yet - I am thinking I will get a length of aluminium angle and put that on, or else a piece of timer and then paint it with waterproof paint.

I could see doing something like French doors with opaque glass so the lite could come thru to the rest of the house. Also double French doors would allow you to open the area up completely whilst doing laundry. You could even leave everything where it is (dryer) and build some storage on the left side. I would image the sink would be very useful - I'd be lost without mine in the laundry room.

I read an interesting comment somewhere, where a lady invited a group of her friends over to lovingly point out all the problems they saw (through fresh eyes) with her home on preparation for sale. She said she was surprised at marks and damage that she had lived with for so long she no longer noticed them. We "owner built" a home previously, and when we came to sell 7 years later, we painted the garage and did those jobs that we had put off, and it became sad to finally see her at her best, at the end, when we could have been living in a completely finished home all that time. I read about a lady who decluttered her home, had it professionally cleaned (build clean, or bond clean) and had a professional styler do her home and she realised just how nice it could be and decided not to sell. :) ta