They have a shop in the city centre and possible one around the M2 diection. They have very good service but not sure if they are the cheapest around. We used Kings in Keady to get our Pram and they would be on the way back down
Try Toys R Us. A lot of the toy shops have great nursery sections where you can pick up lots of bits and pieces such as bedding, changing mats, feeding equipment etc. Toys R Us seem to have a huge selection of baby stuff but I'm not too sure if it's near to Ikea sorry!