I have a 306 hdi dturbo on a V plate with 69k as my other car whilst the cossie is of the road. I have worked on loads of them and know that IF you can find a good one and look after it i will keep on going for miles but it took me 4-5 months to find a good one.

The coolant need changing every 2 years or head gasket problems will occur.
They dont run an intercooler and use oil coolers instead so check for signs off oil and water mixing in the header tank.
Electrics as mentioned but all Pug are known for this.
Auto wipers are known to go funny and a new wiper motor is usualy needed.
High and low presure pumps are known to just pack in as mentioned too.

They are good cars but just like any treat it like shit and it will fuk up on you but look after and you might just get away with it lol

Hope this helps

EDITED : If the one you are looking at is on 81k and is still on its orginal clutch it will probably be due one soon so check up on that and the timing belt should have done or will be due if not