If it has a plastic timing cover then its a belt, metal its a chain. There is no regular change interval for the chain it should last the life of the car although we all know it doesnt. At 36000 it should be perfectly ok.
Edited by imagineifyeswill on Saturday 13th June 15:25
If it is belt the time it has been in requires it to be changed even if the mileage is low (7 years or 70,000m IIRC) so it is down to whether it is a keeper or not to make the decision.