I'm not too sure that this limp wristed, lovey dovey , softly softly approach of yours is going to work....Simples. Catch the boats in the channel. All passengers DNA tested to determine where to send them. Soldiers or civvy volunteers to give them a good going over, with injuries sufficient to render them unable to attempt the return here, and faces so destroyed that nobody will want to breed with them. When word gets back to Somalia or Afganistan, they will stop coming over. Drop them off by parachute, or clandestine beach landing at night.