If we don't sign Colwill, I'd argue that we need to go relatively big on an LCB.
Random names to hope for:
Mattia Viti: 20 year old, Italian U21. Broken into the Nice first team after a decent first season at Empoli. Tall, no obvious weaknesses but would need to work on his ball playing skills...
Arthur Theate by the way, though probably out of our league (joined Rennes last Summer), would be THE left footed CB to sign. Will be the best ball playing defender in the world in a few years and no surprise seeing him on this list.