maybe its a knackered water pump or a oring causing the system to loose pressure maybe, as its a old car and only then little miles in a hands of a elderly driver so ill be concerned about the rubber bits and the fact that engine has probably been lugged arround for most of its life. check for oil or coolant mixing.
i doubt insurance company would do much other than to direct you to a workshop and do check in advance if labour charges of repair are covered or not if they are.
i would also suggest you join a UK peugeot owners forum that way youll have expert knowledge on your particular car as well as all the cheap and good places to get it serviced and to get parts from.