UK Stocks-Factors to watch on May 26

May 26 (Reuters) - Britain's FTSE 100 index is seen opening down 2 point at 7,515 on Friday, according to financial bookmakers. * BARCLAYS: Britain's Serious Fraud Office said on Thursday that Barclays and its former senior bankers will not know until around mid-June whether they face criminal charges over a 2008 emergency fundraising from Qatar. * ACACIA: Barrick Gold said on Thursday that two mines at its majority-held Acacia Mining, which account for some 6 percent of Barr