I'd be happy enough with Ridgewell, only as cover though. I'd like to think we would bring someone else in as well to play CB, but one who's properly equipped to play in the PL. Like Yorkie's said, a player who would ideally fill in for Colo if he's injured/suspended.
As it stands, Williamson and Colo (in January anyway) will be the first choice pairing. Add this someone else, Ridgewell (and maybe Perch/Kadar) and we'll be fine I reckon.