CS
I've done several quick searches and whilst I can find a number of references to Test Trading, all of the links I checked were over two years old, however, a number were on local council sites, which would tend to suggest that it is still available.
From what I can see, Test Trading and Permitted Work may be mutually exclusive, although I cannot confirm this is the case.
Your best bet is to try your local CAB office as they usually have knowledge of these types of schemes. The DWP often seems to be the last place to look for this information, so I'm not surprised they were unaware of it.
Gordon
Nothing on this board constitutes legal advice - always consult a professional about specific problems