(Reuters) -British subprime lender Amigo Holdings said on Monday Chief Financial Officer Mike Corcoran will step down immediately, on a day where its shares fell as much as 62% after the firm flagged potential insolvency. Amigo earlier in the day said it could enter insolvency if a new business rescue plan and a likely rights issue were not approved by creditors and in court, and shares on the London Stock Exchange closed 42% lower at a record low of 3,480 pence. Amigo has been scrambling for survival after a deluge of customer complaints early last year of misselling loans. The London High Co…