FLORENCE, Italy (Reuters) - Britain is not prepared to pay for access to the European Union s single market during a post-Brexit transition period, a UK government source said on Friday. During a speech in Florence Prime Minister Theresa May called for Britain to stay in the single market under its current terms during a roughly two-year transition period. Following the speech, a government source said Britain was categorically not prepared to pay for single market access, and that a commitment to honor Britain s obligations referred only to specific programs during the transition period. 