For those that already own EGLL or EGCC like me, Gary has updated the installers so that they can install in P3Dv4.  I recommend that you head over to the UK2000 Forum and see if what you own is updated.  He will not sell V4 until all sceneries are converted.   I only found out because I went out and checked.   I have loaded EGLL and EGCC not all of his usual features are there but it works and I find it good enough until the next upgrade cycle.

Yes, it is worth pointing out here that Gary is not claiming "full P3Dv4 compatibility" here. He is simply updating each of his airport packages so that they can be installed in the new version without problems. A handful of existing features (animations/windsocks/safedocks) will not work until he builds new versions of each airport at some point in the future.