UK Stocks-Factors to watch on March 20

March 20 (Reuters) - Britain's FTSE 100 index is seen opening 27 points higher on Tuesday, according to financial bookmakers. * BRITAIN-EU: Britain and the European Union agreed on Monday to a transition period to avoid a "cliff edge" Brexit next year -- though only after London accepted a potential solution for Northern Ireland's land border that may face stiff opposition at home. * CAMBRIDGE ANALYTICA: Britain's data protection authority plans to seek a warrant to search the office