Bankrut Station in Prachuap.
Ban Krut has one of the more picturesque railway stations you will see in Thailand. And now the express trains stop daily.
The “Sprinter” southbound from Bangkok to Surat Thani departs Bangkok Hua Lamphong at 07:30, air con at about Bt 350 which includes a meal, and arrives at Ban Krut at about 12:15 (assuming it’s on time).
If your are staying farther north in Bangkok, the sprinter departs Bangsue station at 08:30. Bangsue is the northerly-most subway station.
Surat Thani to Bangkok (northbound) arrival/departure at Ban Krut is 14:15 ish.