I do like the idea of white stools, if you fancy painting the stools. I would personally paint the walls white and hang some bright coloured art (maybe with some yellow accents) - it will brighten the area. If you don't want to spend too much on the paint, either browse through the discounted section in B&Q and homebase, or buy cheap white paint (£4.00 for 5L homebase brand) and mix part of it with a paint tester of your choice for off white shade (like white + beige for lovely warm light shade of roman stone) - you're lucky to have such a lovely and well lit kitchen!

I have lived in two places with breakfast bars in American style kitchens. I found that I tended to spend a great deal of time sitting there so a bar stool with a comfortable back is important. I made mine from pine, copied from some I saw in a bar. I was also given an old captains swivel seat from a yacht so I built a stand for it, reupholstered it and unfortunately left it for the new tenant who liked it. That was one of my favourite seats, to sit in comfort at a breakfast bar rather than balancing without a back to lean on.

I've got exactly a 17cm gap between my chairs and kitchen table which I can just about cross my legs at so the gap is fine is to me. Sometimes though visually a stool can look too high. I love LTS's first stool (it's looking good with the bar fitted!) but it looks a tad too high for me personally so it might be good to see a pic of your bar. i may be wrong but think it's going to be hard to find a fixed seat of 70cm. Counter stools versus bar stools come within whatever height ranges and I think 70 probably sits in the middle of those ranges. I've found one stool a bit higher and one a bit lower if they're of any use https://www.atlanticshopping.co.uk/bar-stools/pacino-stool-white.html?utm_source=gbase&utm_medium=se&utm_campaign=gb&LGWCODE=9488;19372;5285&gclid=Cj0KCQjwjtLZBRDLARIsAKT6fXzJSHprROxntwEN9tgd3HHstXnDNUiFpiQBh1pZTWNtT2BvLo__AS4aAgF_EALw_wcB http://www.barstools.co.uk/a-x-bar-stool-white.html