Northern Ireland is part of the UK, but that's a completely different country from Ireland. Being UK born or based gives you no privileges over the .ie domain at all.
The best thing to do is to watch this great, quick and witty primer on the whole thing Britain/UK/England thing: https://www.youtube.com/watch?v=rNu8XDBSn10
Ireland is part of the British Isles, not Britain (which is England, Scotland & Wales).
Northern Ireland is part of the UK, but that's a completely different country from Ireland. Being UK born or based gives you no privileges over the .ie domain at all.
The best thing to do is to watch this great, quick and witty primer on the whole thing Britain/UK/England thing: https://www.youtube.com/watch?v=rNu8XDBSn10