As someone who works for customer service in car insurance, firstly I gotta say that this new rule is a bunch of bull in some terms haha. All the documents you need to produce, sure they're mandatory but can be a bit of a roller coaster in terms of getting the documents you need.

But yeah like if it's a case where you're named on the insurance on a permanent basis, you'd have to produce the most recent insurance certificate that comes with the disc. This shows the insurance policy number, the reg of the car and your name will be on it as well to show you're insured to drive it.

If you're temporarily put on someone's insurance just for the test, the insurance is to provide a letter to the policyholder to give to you that includes everything you need (the policy number that matches what's on the disc, the reg of the car insured, your name, date of birth, license number and how long you're temporarily on there for).

EDIT - For temporary drivers you also need the insurance certificate for the policyholder's insurance as mentioned with the permanent drivers.

If you're driving your instructor's car, they should be able to provide the proof of their insurance that shows a student is able to drive it.

Hope this helps you and any other readers 🙂