Heads up - hair lightening experiment about to begin

Sick to death of my hair. As part of my beauty spending embargo have been home colouring. To be fair am about 40% grey, maybe more and paying £40+ for a single colour, once even more expensive highlights had been ruled out, in the salon seemed nuts. Of course like a fool used a permanent colour that was way too dark and have been growing out since whilst topping up roots with various shades of Casting Creme, some more successful than others. I really want to go lighter again so today have bought a L'Oreal pre lightening kit and a Casting Creme in honey blond - dark goldish blond so not light blond but lighter than where I am now. Am about to cut off 2 bits of hair, one to test the lightening kit on and one to test what would happen if I just applied the Casting creme semi perm colour. Watch this space. !!