My rule of thumb on whether it's appropriate to call someone fascist: would they label themselves as such? "Fascism" is a notoriously hard to define term -- there was never a "fascist manifesto" the way there was for communism.

Life is too short to argue with someone about what their political beliefs should be called. The British National Party is a bunch of wrong-headed jerks regardless of whether they're "fascist" or not, and every moment you spend arguing with them over whether they're really "fascist" is a moment you really should be arguing with 'em about why their policies are stupid.