I think with your personal knowledge you shouldn't be scared of a dealer. You also have the sale of goods act on your side so at least a 6 month warranty.
Do your research on the dealers and go for it. No reason that an auction is going to be any less risky, even if you might save a few quid on the actual purchase price.
I bought my last car (5 years old, not a Land Rover, sorry) online, sight unseen. Did the usual checks (HPI etc) and it has a full main dealer service history which I could view online. Had it delivered to my home at which point I examined it and was happy to accept it.