Swinton have sorted me out for my son who is at university. Admittedly it is on a basic Fiesta, and I don't know what car you have.
He isn't a named driver, but can be added as an additional driver for up to 90 days per year.
Each session must be for a minimum of ten days at a time, and it works out quite reasonably. A ten day period costs just over £50, or £5 a day.
Longer periods cost less per day, as there are fixed charges per session as well as a daily charge, so short periods are more expensive.
90 days per year is a quarter of a year, which is OK if he is away at Uni a lot.
Give your local Swinton branch a ring and see what they can do.