This morning I finally figured out the airport GSX profile changes required for enabling services for the A380 at EGPF Gate 30 (where it docks IRL). It took a while (as I am a newbie at tweaking GSX).
It involved going into the GSX airport config editor and changing a few size values and switching the gate over from MEDIUM to HEAVY, as well as going into the 3D parking position editor to modify the front wheel parking position and the parking radius. This puts customised position coordinates into the .ini file for the airport, and allows GSX services to become available. You then apply/save these changes back to the airport gsx profile ini file.
It seems to be working now. It’s admittedly going to be a bit of a pain having to do this for many other 3rd airports though, as their GSX profiles and gates may have never been configured with an A380 in mind.