Some proposals for the Britons with regional units from EBII:
http://europabarbarorum.wikia.com/wiki/Kladibiakoi_(Goidelic_Swordsmen)
http://europabarbarorum.wikia.com/wiki/Colgacilioi_(Caledonian_Swordsmen)
http://europabarbarorum.wikia.com/wiki/Eqoreda_(Goidelic_Cavalry)
http://europabarbarorum.wikia.com/wiki/Bodina_(Goidelic_Skirmishers)
http://www.twcenter.net/forums/showthread.php?760603-Help-the-EBII-Team-Screenshots-of-all-the-units-in-the-mod&p=15450247&a