Bit of an update on this.
Ended up plugging the vehicle into a Snap-on Solus Pro ecu scanner (fantastic product by the way!) and my ECU had a logged code of O2 sensor.
After looking at the O2 sensor readings, it is not a constant pulse (as I have been advised it should be), the readings are a bit all over the place!
I have ordered a new O2 sensor along with some other bits from EB spares.
As a temporary fix (if it is a temporary fix!), if I unplug it and drive it for a week or 2 until the new sensor arrives, will this do any damage? And will it run normal ?