For some reason I can't upload a photo which is annoying but would a wall hung vanity work for you, some of them even have side mounted taps

A heated towel rail is fine on a bare wall. Mine is. That vanity unit should be fine too. Just make sure it's sealed on the back edge.

Sanitary ware. I'm having a crisis of decision making. I bought a new sink and vanity from IKEA: https://www.ikea.com/gb/en/products/washstands-taps/wash-stands/fullen-t%C3%A4lleviken-wash-basin-cabinet-white-spr-39891444/ However, it's occurred to me since that it'll take up too much of the room/floorspace, especially as the sink faces you as you walk in. I've been looking at other designs, and the wall-hung sink with a nicer-looking chrome waste could be a much better option. Added to this, if I'm tiling the floor, I'll probably need to buy a new loo, and IKEA doesn't do matching loos. Therefore...where can I buy a basic loo/basin package? What's the difference between a 'toilet and basin' and a 'cloakroom suite'? Should I go for one or two tap holes? Am I wasting my money? Should I just update the taps on the existing sink and tile-box in the waste?

This packing is 600mm wide