Okay so I just changed the ignitor module and coil without doing the rewiring of the melted O2 sensor plug yet and it looks like the over fuelling issue has stopped. Started the car and it doesn't smell of fuel at all and doesn't seem to be running rich anymore on start up. This doesn't really make any sense to me how the ignitor module or coil could have caused so much unburnt fuel. It seemed to have plenty of power and wasn't misfiring under load where I would have expected to see the issue if the coil was bad. If it was getting that much unburnt fuel at idle and low down in the rev range I can't wait to take it for a drive now!!!  
The only reason I changed the coil and ignitor module was because the car switched off when driving and the ECU registered a fault in the ignition circuit. So I knew either the coil or ignitor was dodgy because the circuit was breaking when heating up. If that didn't happen there is no way I would have pinned either one of these as have causing my over fuelling issue.