Khao Lak To Penang?

Hello and thanks in advance for any advice,

I am returning to Khao Lak on a dive boat at around 2pm on march 11. I have several questions. What is the fastest way for me to get to Penang from here without flying? Minibus? Who do I contact? I am considering getting the 1:30 AM train to Butterworth from Surat Thani, but am having a hard time figuring out what the last bus is that can get me there. Is the ticket window at Surat Thani open that late? Where would I catch a bus to Penang in Surat Thani if I miss the train?

Thanks!!

Brandon