Just got a 2002 Peugeot 806 with high mileage - what should I know before taking it on the road?

I recently purchased a 2002 Peugeot 806 with high mileage and I'm planning to take it on some long trips. As someone who's new to owning an older model, I'm looking for advice on what to expect and how to prepare the vehicle for long journeys. Should I be worried about reliability or are there any specific issues common in this model that I should be aware of?