Quick update in case anyone ever searches for similar codes.
A reply on another forum also suggested that the issue was likely to be with the charging system. Before replacing the battery I had a look at the voltages, I was getting 12.4 V from the battery with the ignition on and 15.1 V when the engine was running.
With such a high voltage and with a few of the error codes suggesting that they were from overvoltage I bought a new voltage regulator for the alternator to see if that was the issue.
I installed the new regulator today which was a really easy job, the hardest bit was getting the air filter housing out!
Following changing this I gave the car a quick run and the running voltage had dropped to about 14.5 V so still quite high but a little lower than before.
I've got a diagnostic cable coming in the post and hoping to check INPA to clear the codes and see if they reappear.
If the issue remains or returns I will get a new battery fitted (the current is 6 and a bit years old anyway) and then check the alternator and ground straps as the previous commenter had suggested.