If you want to fly your drone inside an aerodrome flight protection zone, or if your preferred flight plan includes flying through any part of a flight protection zone (FRZ), you are required by law to seek and obtain air traffic control permission in advance.
If the relevant airport is already using NATS’ Airspace User Portal (the AUP is currently undergoing trials at several UK airports including London Heathrow, London Luton, Cardiff, Manchester and Southampton) you can make your FRZ flight application online via the automated AUP system.