Thanks everyone for your replies.
I got to the car and tried some WD40 in the lock and attempted to exercise it, no real luck.
Called a breakdown guy out, he tried something like WD40, maybe a contact cleaner and spent 5 mins trying to exercise the lock, no luck. Got in via rear window.
After opening the door and using the central locking a few times, it freed up the door lock and all is ok now. He says Renault use different types of metals in the lock so they can adodize against each other and cause this.
Glad you got it sorted James, Thanks for keeping us updated.