Febond Blue Grit

So i'm renovating a small second bathroom we have. All new flooring with no more ply fitted and one wall re done with MRP, the two other walls are plastered but in good condition (emulsion removed). I've done some tiling before but was always told PVA however I've seen on a few forums now this can be controversial.

To cut a long story short what I've now done is the FeBond Blue Grit the two plastered walls and the MRP wall....now doubting myself. Will I be OK tiling onto this with medium format tiles using flexible cement? There will be no shower just a bath, toilet & sink. Thanks