Upvc cill cover advice

[HokkaHokka]

Have a cill cover that I'm planning to cut down and nstall over quarry tile. First question is, is the surface ok (or should I remove the tiles) Also, I would imagine the trim to the bottom of the window would need to be removed, is this correct? Any other advice also much appreciated . Thank you so much in advance

 

[Wayners]

On the window sill?

Remove trim at the bottom of window
Clean and sand sill
Use a polymer like Stixall to stick down sill.

 

[HokkaHokka]

Great , thanks for your help