EML intermittent display - Code reader?

Gentlepersons,

Hopefully a quick query;

A few months back our EML came on - lady wife popped into a local garage who found no faults/codes. All well.

Driving from Lancaster to Surrey yesterday it came on for a bit - pulled into services for a stress break (it was the M6 after all!); on restart all was fine, no lights & seemed to be running OK.

This morning it came on again during a short journey.

I know I'm going to need a code reader, but is this likely to be a dealer job, or should I try any semi-competent independent? I'm not familiar with the different types/software, but had VW dealers in the past tell me they didn't have the right kit to deal with a different problem...