Nearest airports are Santiago de Compostela Airport (Lavacolla) and A Coruña Airport (Alvedro).
Once in those cities you’ll have to take another bus line to Lugo. The company that offers this service from Santiago is Autobuses Freire (www.empresafreire.com); and the one that connects A Coruña with Lugo is Arriva (http://www.arriva.es).
Once in Lugo, take a last bus to Sarria (www.monbus.es). The Campus is less than a kilometer away from the bus depot.