UK Stocks-Factors to watch on July 31

July 31 (Reuters) - Britain's FTSE 100 index is seen opening up 3 points at 7271.3 on Monday, according to financial spreadbetters. * RYANAIR/ EASYJET/ WIZZ AIR: A transatlantic alliance between three global airlines will shore up their position in the lucrative UK-U.S. market, shielding them from low-cost rivals and the uncertainties of Britain's exit from the European Union. * BAT: British American Tobacco said on Friday it was not surprised by the U.S. Food and Drug A