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

Carpets would be the preferred choice over tiles.

Try wood and glass. Consider hanging the mirror vertically and about 5" from the sideboard top. You could also move the table under the light fixture, change it out for a chandelier, and put the sideboard and mirror on the clock wall where the mirror could double the chandy which should hang 36" or less above the table top.

You can of course have a furniture repair business add material and refinish. Or you can add a center accent piece of tile, or wood inlay. If you're going from a narrow rectangle to a square, you would need to disassemble the table anyway, might as well do something fun with it.