Waterproof Bathroom wall
It sounds like you're talking about adhesive-coated flexible plastic that one would laminate with. My guess is that you'd have a tough time keeping it properly stuck to the wall. I'd instead recommend a rigid sheet plastic product, one with some thickness, such as this 1/16" x 4' x 8' plastic panel from Home Depot. Cut it to size, glue it in place, and caulk the edges. Should be much more durable.