By Huw Jones LONDON (Reuters) – Britain’s Financial Conduct Authority (FCA) can take too long to act and a sweeping post-Brexit internal revamp to make it nimbler will take years to complete, the National Audit Office (NAO) said in a report on Friday. The FCA regulates about 50,000 banks, insurers, asset managers and other firms in finance, a sector worth 173.6 billion pounds ($218.2 billion) for the UK economy in 2021. The watchdog has spent 317 million pounds so far on a big internal revamp and hiring drive as it adapts to a more powerful, post-Brexit role, and applies lessons from the colla…