horse riding/treking in Kerry/Cork/Limerick regions

There've been a few threads on this topic over the last while, which may help you.

This one focuses specifically on the south of Ireland. Hopefully it'll give you some ideas.

Depending on how experienced the two of ye are, you could go to Clonshire for a cross country lesson. I've been there a few times now, it's great craic, you go out for an hour with a qualified instructor, on really well schooled horses and you get to pop a good few cross country fences. It's a great place, with nice fences, ranging from not so challenging to challenging and depending on group numbers you usually get to have a couple of gos at the fences.

If ye're not that experienced then head down to Killarney Riding Stables and go trekking down there. A girl I go horse riding with has gone down there a few times with her boyfriend who's not experienced, and they've had a great time, she is always recommending it to me.