David,
There are a couple of postings running in "General" at the moment on this very subject.
We have used the CC's Mayday service for a number of years and although we've not had to use them yet, they ticked all the boxes when we were looking to cover our large T/Axle caravan.
As with other companies, they only include UK recovery and as we are going to France later this year, Red Pennant via the CC seems to offer the best service, which is who we will be using.
They provide cover tailored to your needs ie, single or numerous trips.