If you currently have a full UK automatic licence and wish to upgrade it to a manual license, which allows you to drive manual & automatic vehicles, you will need to take and pass the practical, manual driving test, but not the theory test. Your full automatic licence already has a provisional entitlement to drive a manual car, so you do not need to apply for a separate provisional licence.
I will assess your driving and advise you when to book your manual test, which you will be unable to do online, because the DVSA system gets confused by you already having a full license! You will need to call the DVSA on 0300 2001122, with your license and bank card details.
During your lessons and on the day of your test, the vehicle you use will need to display ‘L’ plates and meet the other requirements of a test vehicle.