Update.
The barrel (coil) was replaced (new barrel (£117) and all seems well. So it seems that there will be no need for a new instrument panel / ECU in my case, touch wood.
I did speak to Skospares who offered me a good used barrel for £45 but in the meantime my garage got the new part in earlier than expected and went ahead. Job done I suppose. Skospares also offered the appropriate door locks for £10 each which would have meant using one key only. As it is I've now got two - ignition and doors.
Skospares also offered the full kit (barrel, instrument "pod" and ECU) for £125. I'd recommend talking to them. Very helpful.