I paid £800 for a 2003 mk2 with 79k on it..therefore depending on the condition and milage I would value the car at £200-400
I don't really know much about this model but can certainly throw a few pointers based on my mk2.
Rust:- Make sure there's no major rust around sills etc as it can be costly to repair and instant MOT fail.
Clutch:- Make sure it's smooth all the way down and back, there's no springy feel or noise.
Coolant:- Make sure it's of expected (red/blue) transparent color. If it's brown and sandy textured, it would suggest someone has put in some snake oil therefore suspect an underlying leak or HG failure.
Tyres:- Make sure all tyres are good, and if old check for cracks in sidewalls. The expense of replacing will stand up nicely against the cost of the car.
Brakes:- Brakes should not be spongy and should not lock easily. If they lock easily suspect issues with rear brakes (front doing all the work).
Keys:- Should have red (master) key and blue key. If only one key and no red key, loss of key will mean locks, barrel, ecu etc will need replaced. Utimately you should walk away if this is the case.
I'm sure there's more but will let others add based on expertise...hope this helps and enjoy