Thanks, Dee.
Unfortunately, Kew is a long way from the Isle of Man - and very expensive to get to!!
Looking at the Research Guides, it appears that TNA has information on:
Stalag (Stammlager) – in most cases, a camp for NCOs and enlisted men
Oflag (Offizierlager) – a camp for officers only
Stalag Luft (Stammlager Luftwaffe) – a camp for Air Force officers administered by the Luftwaffe
Dulag (Durchgangslager) – a transit camp where captured aircrew were processed and interrogated before being sent to a permanent camp
But absolutely nothing on Ilag (Civilian) camps?!
Then again, I find TNA almost impossible to get any results from!