If someone has had a provisional license for 20 years but has never used it and since moved address, what exactly needs to happen if the person now wants to take driving lessons?
Do further documents need to be produced including a passport?
It's technically a criminal offence not to notify DVLA of a change of address if you hold a driving licence (even if it's not used) but I can't see Pc Plod knocking on your door if you simply change it now. You can do it online but that means having a Government Gateway ID (which is a bit of a pain to obtain if you've not already got one). So you might find the 'Other ways to apply' link relevant:
https://www.gov.uk/change-address-driving-licence
To the best of my knowledge, exactly the same rules apply to both full and provisional licences. (Since they can both be used for ID purposes, the same security checks have to be applied).