Most people fly into Pisa when travelling from the UK , the art centre will collect from the airport once or twice a day please liaise with them about the pick up times so you can make sure you book the most convenient flight.
The nearest big town is Colle di Val D’Elsa which has buses running to Casole 4 times a day or a taxi costs approx. £20
The nearest train station is Poggibonsi. You can get from Poggibonsi to Casole by taxi or if you take the bus you have to change at Colle di val d’Elsa.
The cost of a taxi is usually around €1,40 per km.