Hi Kathleen,

That engine has a timing chain.

In general, that generation of the Astra is pretty solid, though that's suspiciously low mileage for the age of car so try to get it verified with a car history check or servicing records.

The manual alternative is more dependable, so make sure you take a good drive in the car to ensure its automatic gearbox works properly at all times, with smooth gear changes. 

Then it's the usual stuff like ensuring all warning lights work, but then go out once the car is started. And take a look in the engine bay for signs of coolant leaking as well.

Ideally you'd get the car inspected by a mechanic you trust.