I'd imagine that there will be a few similarities between a caravan towing course and a HGV class 1 course.
You take your B+E test at the HGV test centres! I think there are several similarities on the practical test for B+E, C1, C1+E and C+E. Comparing notes with a relative that had to do a C1 test (Vehicles up to 7500kg) for their job, the reversing round the cone into the box was the same.