New key blade I think should work but you may have a problem in that all focus keys are encoded so if the car is dead locked I can't remember will the blade itself be enough to open the doors.

Worst case I think it would be enough to open the boot and you could crawl in that way and unlock the doors with the handle.

Best off ringing ford and asking. You should be able to get a key blade from them handy enough and just get it cut somewhere like Brown Bros in Dun Laoighaire.