I bought a German WW1 rifle grenade for the missus (don't ask) a few years ago in a fine (if somewhat intimidating) shop in Nottingham, I believe it was this place:
Antique arms, British swords, percussion rifles, German daggers and more - michaeldlong.com, but they seem far from uncommon at Militaria fairs, 'fraid I don't know the situation in Ireland though.
With the way the (ridiculous) law's going, I'd say get in there and find those things you've been meaning to buy soonish, before nanny tells us we're no longer considered sensible enough to buy 80 year old balls of rusty metal.
Cheers,
Adam.