Assuming you're in the UK: you may also wish to contact NATS T&S at Hurn, in which case the ADI APC involves a written, practical & oral board examination. As far as I'm aware, your previous experience is of no interest; the APC is required to determine your current standard based on a rating you already have, set against the present rating requirement. The assessment will determine what, if any, further training you require to meet that standard. Previously, some units have had authority to conduct such assessments themselves; I am not aware of any airports units that still do, as it requires staff & equipement to perform, & takes about four working days of tests, & simulator exposure: few, if any, have the resource to manage it. NATS don't offer an APP APC, as far as I know, just ADI, Area & APS.