Right, so today I stripped the passenger side down and looked at the module, and sure enough the solder had cracked but unlike the driver side it was quite bad, anyway, after re-soldering the joint and putting it back in the car the central locking now works as it should along with the passenger door light etc which didn't work! All I need now is to wait for my lock repair kit to repair the drivers lock.
One repair down, about a million to go!