hi i have a lady who is around 80percent grey but uses box dye blonde id say around a 10, very light but a bit yellow. she wants to break it up and add a little something to it. iv gone with 10/38 koleston for roots and 88/03 color touch plus for some fine low lights. iv not tackled grey before and im worrying about result how do we feel about those colours will it work? thank u xx