Britain's FTSE 100 index is seen opening up 42 points on Friday, according to financial bookmakers. * BHP: Anglo-Australian miner BHP said on Thursday it had begun to review contingency plans ahead of a possible strike by union workers at its Escondida copper mine in Chile, the world's largest. * GOLD: Gold prices held steady near a one-year low on Friday amid a resilient U.S. dollar and were headed for a fourth straight weekly fall. * OIL: Oil prices were