PhilM - just write a letter to the CO of the St Athan VGS expressing your desire to become involved and your background.
You'll very likely get asked along on a trial basis to make sure you are not a knob and as long as you have no problems with washing aircraft, a bit of sweeping and a lot of tea making you'll be in within 6 months.
My experience with the CAA was just before JAR implementation back in 1999. They then took a rather more pragmatic view of things and counted all my Vigilant time as Group A (as was

) and told my FIC course provider to give me just as much tuition as they thought necessary before sending me for test.
To be honest the high CFS checked standards of the Vigilant world couple to holding a PPL for 5 years was enough to make the CPL and FI modules a combine 5 week doddle.
But it probably ain't under JARs any more!
Cheers
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