There are no bus routes serving Stanford, north of the M20 except for a dedicated school bus service 10A. Stagecoach route 10 operates between Folkestone and Ashford via Hythe and stops at Newingreen. For a timetable, see here.
Note that if catching the bus at Newingreen, the bus stop is in Stone Street for those buses that go via Lympne and outside Holiday Extras for those that bypass Lympne. Check on the timetable for which is which.