I find the best parking in Newcastle is either Manors or the Quayside multi stories.

No need for an app. Card only. Check in and check out with your card. You only pay for the time you are parked. No overpayment or worries about getting back in time before your time runs out.

Ten minute walk to the centre of town. Watch out for the tripping hazards of the hire electric scooters which get dumped everywhere. Also try to avoid getting run over by the take away delivery bikes.
Safer to shop on line me thinks!!!

Downside of Manors is possible kerb rash on your alloys due to high kerbs at the entrance and exit.

Don't know of a Metro station at the Metro Centre.