Just bring the bulb with you when you go to buy the new one. The outlet is obliged to take it off you as they have just likely charged you 50cent towards the Producer Recycling Fund (PRF) to do so on the new bulb.
If you don't bring back your electric items you're giving someone free money.
It's all at
http://www.weeeireland.ie/
http://www.weeeireland.ie/retailers.htm