My hairdresser's away for a few weeks and if I don't do something about my hair soon I'll look like Philip Schofield. So, I'm about to attempt a home dye for the first time...eek! I have very, very dark brown hair with quite a lot of grey root and some old-ish bleached highlights which have been dyed over several times so aren't really obvious. I last had my roots done about 10 weeks ago. Should I just do my roots or the whole length of my hair? My hair goes below my shoulder blades. Will there be enough? Is the reccommended time accurate?