Looking at what spec there is Im assuming that this has to be one of the 3Bar pumps that are sold for most domestics.
Your right the best bet is Probably to Insulate the service cupboard.
What Clarke pump do you use? I had a look at Machine mart earlier and the range is equally confusing..
What I may do is mount the lot in the Van and simply feed a cold supply , a 240v supply and a return pipe out to the van . and refill at the end of the day..