Right. If you want to dye your hair at home with professional hair dye, here's how its done. The best one for grey hair (even partly) but for 100% non-fade coverage is Loreal Majirel.
You can buy it from Capital Hair and beauty if you say you are a student on checkout. They don't check. Its just a box ticking exericse. Failing that, browse there and buy from eBay.
For a more natural result, you'd mix a bit of golden blonde with copper blonde. Getting the right ratio can be tricky but half and half is a good place to start. Both shades cover 100% of grey so shouldn't be garish.
Tethers, I would suggest that you buy some 7,3 and some 7,4, and some 20 volume peroxide. Do a strand test. Mix 1/2 a teaspoon of 7,3 with 1/2 a teaspoon of 7,4 and 1 and a half teaspoons of 20 volume (6%) peroxide.
If it seems too ginger, you need less of the 7,4 and if it seems not ginger enough, more, etc. But keep the ratio of 1 part "dye" from the tube to 1 and a half times peroxide from the bottle (about to link). If it just looks wrong or dark or weird then back to scratch, PM me with what it was that was wrong!!!
7.3 Golden Blonde
7.4 Copper blonde
[[http://www.capitalhairandbeauty.co.uk/hairdressing/colour-bleach/peroxide-developer/hi-tech-cream-peroxide-1-litre-20vol-6.html 20 volume (6%) peroxide)
So just to reiterate: 1 part dye to 1.5 parts peroxide.
So if mixing 2 colours - 1/2 teaspoon one colour, 1/2 teaspoon of another, 3 x 1/2 teaspoons (one and a half teaspoons) peroxide.
I am not a professional hairdresser, I haven't seen you, so do a strand test before you do your whole head. And do an allergy test, particularly if you have tatooos.