I have an openended emac service plan at £32 a month, which I can cancel at any point for a small fee, I am not locked into any length and it will coiver my yearly sevice and provide discount on spares and mot. It should be possible on all 3+ XFs (mine is a 61 3.0D S faceliftwith 115,000 miles). Probably can find it cheaper at independents, but I can't find a jag specialist that I can get to an from without spending hours in public transport. The main dealer isn't near either, but they provide a load car included in the monthly pay, so I can make it in half an hour from and to them.
Service has to be done each year even if you only do 5000.