Hi there, I would definitely go for glass & not tiles. Glass is much easier to keep clean! As for colours, if you have French grey units you could look at a slightly iridescent silver which would compliment well. Be careful with some colours if you are going to be a bit bolder as they will reflect & alter the appearance of the French grey on the cabinets. Get some samples & look at them in different areas under the units - the corners will look darker/lighter depending on natural light & if you have recessed lighting under the units.

I can't imagine tiles, the kitchen looks sleek, I'd be more inclined to do a glass splash back. Not sure on the colour though!

Running the upstand behind the hob looks absolutely fine, seen it plenty of times and customers have always been happy, the only slight downside is large pans and woks can be up against the upstand as its thicker than your tiles but thats being really picky. Personnally i prefer this look then stopping the upstand, then stepping back for your splashback tiles and then stepping forward again and restarting the upstand and its easier to keep clean as well with no little corners for dirt to get trapped.

Hello, Congratulations on your new kitchen, we hope you're enjoying it! We understand that choosing kitchen tiles and backsplash could be confusing, there's so much in the market! You could go with a similar material you've used for the worktop, so it feels and looks continuous. You could also go with a mirrored look to expand the space, visually. We love Kit Kat tiles, they're making a comeback in the market. I'll attach a few images so you can get some ideas! We are Bespoke kitchen and wardrobe designers and provide free-of-charge initial design or quotation services. Our showroom is based in Notting Hill, London, but our services all over the UK.