Subfloor prep

[goz]

Hi guys after some advice on a prospective job. I have been told that the floor to be tiled is kitchen floor. Its floor boards over boarded with ply ( not sure thickness ) and slc on top. Trouble is in two parts of the floor there is a concrete hearth thats lower than the overplyed floor boards. The floor to be laid is granite. How would you guys look to prep this? I have not seen it yet but wanted to go with a few ideas just to be more informed.
Thanks in advance

 

[Mark S]

Is the hearth staying in?
Is the slc in good condition, no cracks etc and still well stuck to ply?