Has it got a full service history, and are you buying from a dealer? (LR or otherwise) and is there any warranty being offered?
TD5's have a few regular problems: Oil on the engine loom and ECU plug, Dual-Mass flywheels breaking up, cracked cylinder heads (fuel in sump) and plastic dowels for the cylinder location which don't locate.
Apart from those, the normal Disco items apply re noisy transmission etc etc. You've had one before so should know the ropes.
Peter