Try and look for signs of wear and tear, to better determine the milage. Obviously rust, as mentioned, on sills, filler cap, under the plastic arch covers etc. maybe even worth jacking it up on a corner to have a poke about at sub frame n things. Dont be shy. With a car of this age anything could have been changed, so many times over. But have a look at the interior condition, the bolsters (particularly the drivers seat) may be worn through, how polished is the gear knob and steering wheel? how worn does fabric etc look?
The kind of use its had (occasional long trips, or frequent short blip over town) and the fact that its 20 years old will make determining the age more difficult. Have a search for buying tips, it may be in the mk2- maintenance section, and obviously pay what its worth for the condition its in.. Would be nice if you've found a low miler!!
Ive been learning to do more and more jobs on my car, building confidence and experience as i go. They are easy to work on, despite the 20 year old seized bolt factor!
Good luck.
oh, one thing i have learned, that may not be in the buying guide.... pop the bonnet, and look for a wax line over the top of the wings, along the line of bolts- wax seal= original wing, no wax means panel replaced (tho a used original panel would have the seal).