Learner driver car insurance is a standalone policy, so you don’t need an existing or main insurance policy.
It's separate from the car owner's insurance, which means it won’t affect their no claims discount if you make a claim.
Note: a learner driver must be supervised by a suitable person, aged over 25, who has held a full UK licence for at least 3 years, and will only be covered whilst being supervised to learn to drive with the supervisor in the passenger seat.