Hello, I am tired of dying my hair. At the moment it is an unnatural red/brown. My regrowth is very grey with an ash brown cast- very cool toned. I would think I am 70% grey. I want to transition now but I am unsure how to proceed. I want to go lighter but will need to strip out the colour first. What is the lightest/ coolest shade of brown that I can buy that will go over bleached hair and will allow me just to grow the grey in?