Although the Freelander 1.8 generally gets a bad press, actually it's not so bad.
The cylinder head gasket problems are well documented, however the biggest cause of the head failure is insufficient coolant circulating in the head during the warm-up phase.
Land Rover modified the hose and thermostat arrangement and issued a Technical Bulletin to this effect (see
http://lrch.nl/node/1000) however even now I see vehicles without this modification.
It is important when looking at a potential vehicle that you check the coolant level and if it were me I would have a "snuffel" or CO test performed to confirm that there are no exhaust gasses in the coolant.
The viscokoppeling problems and testing are documented in the kennisbank.
The other annoying things on Freelanders are the window mechanisms fail so try them all, including the rear window and sunroof if fitted.
All the tyres must be not only the same size but also the same make. This is very important as different makes of the same size are different sizes (yes it's bizarre but believe me it's true).
Water comes in via the antenna and sets the interior sensor off on the alarm.
The heater matrix leaks and although it's not an expensive part it does require the whole dashboard to come out so check the middle of both footwells where the heater fan is to make sure there is no sign of coolant.
Window wiper mechanisms fail from time to time so both wipers should move if one of them is pushed slightly upwards.
There are other features but I could make a list like every other Land Rover product.
Rob