The article was originally published some time ago in "Wargames Illustrated", to coincide with the launch of their Sudan range, IIRC and is probably the best intro to British Sudan uniforms you could ask for - especially as it's free
If you can get hold of issue 29 of Wargames Soldiers and Strategy [Jan 08], it has a large feature on the 1884-5 campaign. There are loads of pics of the Perrys' collection, with several of the Naval Brigade, which will give lots more painting ideas.
Apologies for the pic's large size, BTW. I don't know how to re-size pics when linked from other sites....