Preparing plyboard base for tiling. Help.

I have replaced a low level WC with a close-coupled WC and now wish to tile the wall behind the WC cistern area. The wall is made from 18mm plyboard and covered with a reasonably thick paper. I have some questions that I would appreciate some advice on?

1) What is the best way to remove the paper from the plyboard? I imagine that it would be unwise to use a heat gun as it would be likely to cause the wood to swell? Should I dampen the paper? Or could I use a sander?

2) Once the paper is removed what steps do I need to take to prepare the plyboard for tiling? Is it necessary to use PVA for what should be a dry area?

3) In order that I could get access to run a new water supply pipe at a lower level to the WC I have had to cut a hole in the plyboard of approximately 9 inches square. Can I supply a 9mm plyboard panel to fit this hole or should it be 18mm? If I can, is it possible to glue it into place using Gripfill whilst being held by a couple of batons until the glue is set?

Thanks very much for any help.

Please, please, please help . Not that I am an unctuous, ingratiating brown-nose toady or anything, but I really could do with some advice on this. Thanks again.

calm down fella

1: warm water and scape away.

2va wont harm it let it dry but try to use a latex based adhesive(movment in wood)

3: screw fix batton to rear of hole through existing ply then screw the 18mm ply to the batten so u have a flush finish,

hope this helps

Thanks for the advice, Tonyg.

Had a couple of Budvars then followed your 3 steps and now got a decently tiled wall. Cheers