Tiles are one way to introduce some pops of colour in your kitchen. If you are worried about the grout discolouring, use epoxy grout which is more resilient to liquid staining. Also, if you use a coloured grout, discolouration will be less noticeable. If you choose textured tiles with rectilinear edges, grout lines are almost invisible. Using tiles can look more traditional compared to glass or stainless steel. The problem with stainless steel is keeping it looking good. Drip marks and grease are instantly noticeable. Glass is less obvious when splashed. They are both more industrial and modern looking. What about using the same material that makes up your worktop as the splashback? Most manufacturers of manmade worktops also do an 11mm thick splashback and upstand.

Thanks for the replies so far. I do think I want at least a double but I will need to be flexible if the room is too small. I have attached the layout, it is labelled bedroom 2. As mentioned it is a small house in general, so I am not expecting much rent but I may as well rent it out. On a side note, I also would like to redecorate the rooms as the current laminate flooring is damaged. I was thinking of getting wool carpets as they make the room cosy and warmer whilst also reducing noise from downstairs. Any nice combo of colours for small rooms? Lastly, any ideas what to do with the tiny room (bedroom 3). Ideally want a single bed in their but it will rarely be used so would be great to find some way of making it a study with the occasional place for someone to sleep. It is tiny so that is asking for a lot!

i meant to have the bed over the existing wall and part of the alcove like this, with the blue bit being built to look like a wall, but with access through a simple door... Depending on type of bed headboard you could have recessed shelves built into the storage above and/or beside the bed to act as bedside table.

Perhaps you can use breathable lime render on the old parts and keep the new extensions cement render?