If you want to reach Manciano by train, you can use the lane Roma -Pisa and get off at Albinia Station (about 30 minutes from Manciano by car), or at Montalto Station( about 37 kms from Manciano). Otherwise, you can choose the Orvieto station that is 70 kms far, but offers other trains.
If you arrive in Grosseto you can get a bus for Manciano. From Grosseto, you can also go to Florence or Siena by bus. Visit Tiemme website: http://www.tiemmespa.it
Here, you can download the timetable
For the southest area (Lazio), you can use the service of the Cotral s.p.a. Visit the site http://www.cotralspa.it
Aeroporto Galileo Galilei di Pisa, Aeroporto Leonardo da Vinci di Roma Fiumicino, Aeroporto di Roma Ciampino Giovan Battista Pastine.
For the bus from Roma Fiumicino: