I have 2 student children (19 & 21) who are away most of the year. What is the cheapest way to have car insurance cover for the weeks (or some of the weeks) they are home during the summer, xmas and easter. Adding them as temporary drivers is fairly expensive and can only be done for a limited number of days. Adding them permanently again is expensive and seems wasteful as most of the year they would be away and not use the cover.

Many thanks for any help or advice give.