I have read that there is a good chance it could be a gummed up egr valve. Does this sound likely and is it worth giving it a de-gunk?

unlikely to be EGR as the spanner symbol on vauxhalls although is a management fault its not necessarily a fuel related problem, this will usually trigger the EML lamp (engine symbol)

The spanner symbol is a vauxhall specific fault code and needs to be read with a suitable code reader as it won't be an EOBD code.

If its going into limp mode then it needs looking at ASAP, could be any number of problems, these are not without "usual faults"

Te ECU's can and often do cause problems as they are mounted on the engine, (just where you want your expensive ECU to be mounted...Not)

but until you have it plugged in you won't fix the problem.

My money is on a brake light switch on this model the symptons really match (common fault on these) Regards Micky-bo

Ok, plug in been done, faults show as turbo boost solenoid, air flow sensor, glow plugs and egr valve.

I am going to replace the glow plugs and try cleaning the maf sensor and egr valve and see how that goes :). Thanks for the advice so far :)