Seamus Colemole
Previously deathbyropeandglass
you need provisional insurance so both the person driving and the passenger are insured and the passenger has more than 3 years experience
And the person "instructing" has to be over 21. Other than that anyone can teach anyone else to drive.
Obviously you still need to take a test and be passed by an authorised examiner, if you pass you can drive on your own.
But on a provisional license you need someone over 21 who passed their test more than 3 years ago.