UK Stocks-Factors to watch on April 30

April 30 (Reuters) - Britain's FTSE 100 index is seen opening 17 points higher on Monday, according to financial bookmakers. * GLENCORE: Glencore's mining subsidiaries in the Democratic Republic of Congo have been served freezing orders for alleged unpaid royalties of nearly $3 billion by a company affiliated with Israeli billionaire Dan Gertler, Glencore said on Friday. * SAINSBURY'S: Sainsbury's and Walmart's Asda are in talks to create Britain's biggest supermarket group, a