Just check the usual, as you would when buying any car.
Im not too sure about the 1.4 engine, so will let someone else awnser anything specific to look for with that. Model specific stuff that i can think of;
rear wash/wipe
if it has climate controll - screen flashing on startup (means theres a fault)
a/c works
all the gauges read 0 when the ignitian is off, and work properly when running
Think thats about all I can think of for now. The only other advice I can give is to check the condition of the draw under the steering wheel where the OBD connector is. If it is warped/misshapen and looks like its been pulled out a fair few times - its probably had a fault in the past (and could still be there). Take a copy of vag com to scan for any codes.
Hope this helps, Nick