Decide storage at layout stage
Storage that is planned with the layout costs very little; storage added afterwards costs floor space. Before fixing positions, list what actually has to live in the room - towels, cleaning products, daily toiletries, spares - because those four categories want different places.
Vanity units versus pedestals
A vanity unit converts dead space under the basin into the most-used storage in the room, and hides the trap and supplies. The trade-offs are a slightly larger footprint and a waste that must be repositioned. Wall-hung vanities keep the floor visible, which makes small rooms feel larger and makes cleaning quicker.
Recessed niches
A niche formed into a stud wall during first fix costs almost nothing and removes every bottle from the shower floor. It must be planned before boarding, tanked as part of the shower waterproofing, and given a slight fall so water drains out rather than sitting on the shelf.
Mirror cabinets and lighting
A mirrored cabinet doubles as storage and the room's main light source when specified with integrated, correctly rated lighting. Depth matters: anything over about 150mm starts to feel intrusive over a basin. Any electrical item must suit its bathroom zone and be installed under Part P.