advice as above but to reinforce the advice about MOT - it is only an accurate assessment of the car at the moment it isi issued, it isn;t some magic shield against faults, significant failures or bent sellers once it is outside of the test station. You can't even be sure its the same tyres on now that were the ones on at MOT, do not trust it or give any value to it other than as a legal necessity to be in posession of.
Another place where vehicles can start to rust out from is around the numberplate, particularly around the screw holes if it is a screwed in one and under the rubber seals around windows. As far as you can, get to look behind the plate and under these seals.
suprrised nobody has mentioned service book or receipts for servicing, work done etc. have a look in the glovebox to see if there are any manuals, bits of paperwork the owner has left in there or ask for them. again a good hint as to what may have gone wrong with it, if anything, and maybe a mileage confirmation or to see if its been left unused or fluctuated over the years that might be worth asking about.
Although with all of the above. its a 13 year old car, there will be bits of stuff gone or going wrong and the service schedule has probably become less and less important as it has aged.