Not quite wallpaper - sheets of doll's house type paper, to attach to bare ply. Plan A is 50/50 white PVA and water, which is similar to 'school' glue. Straight PVA would be overkill. Plan B is ordinary wallpaper paste.
Question is, should I prepare the ply with a coat of something first? Perhaps 50/50 PVA/water or wallpaper paste? Areas range from, say, 10 by 8 inches up to 96 by 16 inches.
(This is much more fun than thinking about that poxy cracked bath, which can wait).