Husband having spoken to the RAC (who we had to call out - again - last Saturday) and done some research, it seems the car has, potentially, much more serious and expensive problems than first thought. The work being done by the local garage next Tuesday will only address one lesser problem, not the more serious one. It will, hopefully, enable the car to be used for transporting the stuff backwards and forwards to/from the caravan, so we can finish the work there. After that, we will have to get rid of it (the car that is, not the caravan!) - we cannot afford potentially expensive repairs on a car we no longer trust. At least - hopefully (I have to keep thinking that) - the car will have fulfilled the purpose we bought it for, before we get shot of it and get another, hopefully more reliable, one.
I know there's always a risk when buying a second hand car, we have no real way of knowing whether it has potential problems that the seller has seen fit to conceal. Or the car may develop new problems in the future, which again we have no control over. But having had a couple of cars in the past few years that have caused us no end of headaches and expensive, ultimately futile, repairs, we don't want to have to go through that with this car.
Bloody nuisance, and a worrying one at that.