To be honest, not a great selection of big furniture places in Newry.
Land of Leather is in the retail park beside B&Q on the Newry bypass. There used to be another place beside it (Harvey's, where we bought some of our own furniture, but it seems to be closed at present).
There's a few places on Coes Road in Dundalk that might be of use.
Atlantic, Harvey Norman, Wogan's, Frank's Furniture, Frank's Carpets, National Tile, Tubs&Tiles, Right Price Tiles, a lighting showroom and I think possibly a few more furniture and flooring places. These are spread out between two different retail parks on that road.
Take the "Dundalk South" exit off the M1, take a right at the roundabout and head on past Xerox, and the new hotel that is currently under construction. The places I mentioned above are on the right hand side.
Hope this helps.