Blonde highlights, greasy roots, dry ends - and build up of sebum on scalp.

What are the best shampoo ingredients/brands (I'm in the UK) for dealing with my scalp issues, but not affecting my hair colour? I wash my hair every day because if I don't it looks like you could fry an egg on my head. I also occasionally suffer from hideously painful cysts on my scalp, which I'm not sure whether they're caused by my greasy roots, or just bad luck. Any hints/tips would be appreciated.