I'm not a fan of wallpaper, though I'll admit there are some powder rooms on Houzz with beautiful, two-tone wallpaper that I love. The last time we bought a house we had to choose between two equally desirable, quite similar vintage houses--one with wallpaper on every wall (even in the hallways!) and one with painted walls throughout. In both cases we planned to repaint in colors of our choice, but we bought the house without the wallpaper because it was simply less work to repaint the painted walls than to strip a house full of someone else's tacky, outdated wallpaper. So by all means use wallpaper if you love it and will be in the home for awhile, but don't expect anyone else to appreciate it when you sell. Wallpaper (like patterned fabric) is just too individual a preference to translate easily into someone else's aesthetic.

How do you like your black tap? I was itching to use black in our home but my husband is against it. Thinks they won't stand the test of time. He's probably right haha

I am just wondering whether it is a good thing or not to go with solid colours like the dark blue (prussian blue), grey floors and white on other walls all in tiles. I see that a lot of designers seem to do a pattern on one wall, but I haven't found one suitable and whatever I do, I just don't want it to look out of date in 5 years time. I am not sure how about much of the prussian blue tile is appropriate in order for it to be noticeable but not too overpowering.

I think some sort of extraction fan is essential to eliminate cooking smells and prevent build up of grease in your room. Especially in an open plan area. Unless you live in a climate that Is warm all year around you are unlikely to want to open the window every to you cook. Have you thought about a down draft extraction fan? They pop up from the bench, usually behind your cooktop. Different brands make them. Generally high end and more expensive than a canopy type rangehood but could solve your dilemma.