Thanks sdnj33, I thought there might be an overnight service but I didn't want to take a chance and run the risk of being stranded. The school I'm attending in Granada has since e-mailed me a timetable, and it turns out you can view timetables and book tickets online for Continental Autos, url: www.continental-auto.es . I think this is one of the main bus companies, but there are others. There are also a number of services to Cordoba for citygirl, including ones from Granada, so click on horarios y venta de billettes and select "Andalucia" under "Lineas Regionales".