Hair dyeing help needed!

[RedBushedT]

I usually get my hair coloured at a salon, but haven't been able to get an appointment with my hairdresser. My roots are now almost 2cm
Long. Eek
Natural colour is dark drown, it's coloured a few shades lighter copper/auburn.
I've bought a permanent light auburn dye..
Can I use it? Or will I end up with a right mess on my hands? head

I dye my mousey brown hair auburn and find that the colour is different every time. Some brands have more brown tones, some more copper. Would you mind going either way?

I'm happy either way, just a bit worried as to whether the roots will still be obvious once I've dyed it.
I've been crap letting them get this bad!