If you want the seats to swing out from the island be sure to check that the island is substantial enough to take the load, also that the island is well anchored to the floor. If you consider the arm is for example 2 feet long, then sitting on the extende seat will be the same as applying your full weight to a crowbar, two people sitting on one side would destroy a normally constructed island. Similarly, if fitted to a wall make sure that they are anchored well and that the wall structure is suitable. A nice idea to save space though

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

Out of all the ones you’ve listed I like the one from Perch and Parrow but I’m confused when you say footprint within 48x48cm and this one is listed as 42x42cm. Incidentally I found them cheaper here: https://www.costco.co.uk/Furniture-Home/Dining-Room-Furniture/Chairs-Bar-Stools/Gallery-Palmer-Brown-Faux-Leather-Bar-Stool-2-Pack/p/263151 Also found this one: https://www.wayfair.co.uk/furniture/pdp/selsey-living-hoker-65cm-bar-stool-tcdv2652.html?piid= And a bit of a wild card but the cantilever might make it extra comfy: https://www.argos.co.uk/product/8835576 Also have a browse in the Houzz shop. They have lots of barstools so you may find something there.

Yeah, I can see why- there's not much view but two doors at the front is unusual even if one is behind a fence. Forgive the crappy drawing below but our current fence is in orange and my (probably not too accurate) extension is in blue. We thought we'd keep bins in that front part with a gate to the front door. When we thought about extending we always assumed it would just be adding to make it a bigger rectangle if you see what I mean but architect said that extensions need to be subservient to the original house, hence the weird shape.. I posted the kitchen by itself to get some ideas in isolation- if anyone else is reading and didn't see the other thread the archi's idea of the kitchen is below too but I didn't feel like it worked.