UK Stocks-Factors to watch on May 22

May 22 (Reuters) - Britain's FTSE 100 index is seen opening down 4 points on Tuesday, according to financial bookmakers. * TULLOW OIL: The production vessel at Tullow's flagship Jubilee oilfield off Ghana's west coast will shut down next week for 21 days while it undergoes repairs, the country's power utilities said on Monday. * BRITAIN RAILWAY: Britain's Department for Transport (DfT) encouraged "ambitious" bidding on revenue projections for the failed East Coast main line cont