The only time i had a problem with my employers not liking the colours i dyed my hair was when i worked in video drive in. Nothing was metioned in the interview or the terms i got, but then again the owner didn't like the fact i had my ear pierced and wanted me to take them out, that never really happened. I worked for six years at Mcdonalds and never had any problem with them over my hair colour, ok i wore a hat but with shoulder length hair you could still see it. I think your right to stand up for what you believe is wrong, but be careful about how you go about things, i would suggest a trip to citeizens advice in Market Street and see what they say. If you have a copy of your terms of employment take it along with other documents about your situation, and they should be able to help you. Good luck man.