From what I understand, Old Glory 15s (which now make Black Raven) is a separate company from Old Glory 25s. Old Glory UK is associated with Old Glory 25s, so I don't think OGUK would have Black Raven.
For other ideas, 15mm.co.uk's HOT & Tabletop lines, Magister Militum's Chariot & Blood Dawn lines, Mirliton, Irregular, Essex & Splintered Light both have 15mm crossbow armed dwarves. Irregular has a bow armed dwarf