By Ashley Cowburn Rishi Sunak faces a new by-election nightmare as the suspended Tory Scott Benton announced he was resigning as an MP. The Blackpool South MP was caught by an undercover newspaper sting offering to lobby ministers on behalf of gambling investors. In December, the Commons sleaze watchdog found that he had committed an “extremely serious” breach of Parliamentary rules and recommended that he face a 35 day suspension. After refusing to step down he had been facing a recall petition in his own constituency which could have led to him being kicked out of the Commons by his own cons…