(Reuters) - Britain's biggest pizza delivery company Domino's Pizza Group Plc on Wednesday reported a rise in fourth-quarter group system sales, helped by higher demand in UK and Ireland and warned that it expects significant impairment charges for 2019.The company, which is looking for buyers for its international operations, said group system sales rose 3.7% to 352 million pounds ($458.09 million) in the fourth quarter ended Jan. 29.