Congrats Mate! Nice FF Loads of great advice on here, so enjoy the FF experience. Also a lot of pain, but that comes with the marque  SDV8 AB MY 2019
SDV8 VSE MY 2015 - Gone
5.0 S/C AB MY 2010 - Gone
4.2 S/C VSE MY 2006 - Gone

As long as you keep up with the oil servicing the engine should be pretty bullet proof. The issues can be the egr valves breaking and ruining the engine and turbos going but theres always risks with any car. Gearbox is pretty solid but dependent on the mileage and if its not been done a genuine fluid change and filter is recommended. Outside of that check the upper tailgate for rust and the rear arches. Suspension components may start to go at that age too but if your handy enough with the spanners doesnt cost much. A good diagnostic tool is helpful too the gap iid is recommended. Oh also lots of faults in ome go is usually a low battery or the alternator packing in. Have a good search on the forum lots of info. And they dont need to cost thousands, well mine certainly hasnt in the 3 years ive had it thats for sure. Current 2007 TDV8 Vogue Buckingham Blue

Looks good and welcome! In addition to your point about friends mentioning high service costs etc, I expect you’ll also be inundated with people asking about fuel economy. The reason being that they think they can ‘win’ on this one. My tip, 4 V8 Range Rovers, 1 V8 90 and 1 Discovery in is to say ‘I don’t know - it’s not really an issue for me’.
This new tact seems to work!