Snap it up.. Decent warranties from WD and as long as it's been serviced / has a good mot they won't even inspect it beforehand. You can also use the main dealer to do any repairs (which unfortunately is stratstones in Donny..) £841 wouldn't cover the cost of one airbag if it's leaking.
Try and drive it every day, they don't like being left stood & tend to throw up lots of warnings on the dash when the battery is anything but 100%
Also don't just drive on road - you've got to try it in the rough, they are the best 4x4xfar.. There is no other car that has the same on & off road presence in one package - enjoy!!
Ps if it's got the factory phone you'll also have voice control for the sat nav which always impresses people. You'll also want to upgrade the nav drive from cd to DVD (2 minute job) which gives you better maps, it's quicker and you gain postcode entry