Are my masonry wall suitable? - Tile Advice

[One05]

Hi all 1st time posting, im just in the middle of redoing our downstairs cloak room and have just taken off the ceramic tiles which where only half way up the walls which means some of the skim plaster has come off and left 2 levels of wall.

The walls seem solid but the top half is matt emulsion. Can i just prime the walls and skim the bottom half of the walls? if so what primer and type of skim should i use.


The room is only 10.6sqm and the floor which is concrete is 1.22sqm.
We are looking at using a porcelain 10mm thick 600mm x 600mm the super white for tiling the walls and floor, do you think this is an ok size tile for the room dimension its only because we intend on using the same tile for our kitchen and dining room.

I have tried to attach some photos.

 

[SJPurdy]

That thickness of porcelain tiles weighs more than the recommended limit/m2 for tiling over plaster walls (and especially painted ones). I recommend removing all the plaster; fitting plasterboard (don't skim) or a tile backer board; and then tiling.

 

[One05]

Thanks for replying sturdy,
I was hoping not to go down the backerboard route just because it will shrink the room even more but if needs be then that will have to be. Even if I used a smaller tile ;ie same tile but 400 x 200 would that make a difference?
I have read that the backerboard comes in 12mm for walls and 6mm for floors, would I be able to get away with using 6mm board for the walls as I'm sure the finish product will come past my door lining.