Faenaris -- as everyone else has already convinced you -- the national variety (and variety in general) in Dominions 3 will be more than enough to sate your desire for fantasy. If still you really want that Warhammer-esque experience, I've produced four relatively-balanced nation mods based on Britannia/Empire, Wood/High Elves, the Vampire Counts, and the Dwarves. You can find 'em in the mods sub-forum on here once you get the game. Have fun playing!
(Sorry if I missed a post that makes mine obsolete)
There was a mod for Dom2 which featured 2 full-fledged orcish tribes, with a bit of work I'm sure it can be adapted into Dom3 and you can have your Orcish Experience (TM)
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I'm in the IDF. (So any new reply by me is a very rare event.)