Sharmanat0r,
EGPK and EGPX are the ICAO Location Indicators for Prestwick Airport and the ATC centre.
The ATC centre is located just off the airport, on an industrial estate, in the angle of the 'L' shape formed by the 2 runways.
If I remember correctly, on leaving the airport turn left towards Prestwick. At the end of the dual carriageway, there is a roundabout.
At the roundabout, head down between the flats along Shawfarm Road.
The centre is near the end of this road on the right-hand side. It is about 1.5 miles from the Terminal building.
Good Luck!
