By Kate Holton and William James LONDON (Reuters) – British consumer energy debt is already at an all-time high, a survey showed on Wednesday, with six million households owing cash to providers even before bills leap in October and again in January. Britain is bracing for already high energy bills to more than triple this year, with charities warning that millions of people could be forced into poverty if the government does not launch a multi-billion pound support package to soften the blow. The looming crisis has put the two candidates to become the next prime minister under pressure to set…