Book ferry to Koh Phangan?

[cocoonclub]

I booked a last minute trip Bkk — Suratthani— Koh Phangan — Koh Samui — Bkk. 
 

Do I need to pre-book the ferry to Koh Phangan and the boat to Koh Samui? When traveling to Koh Phangan I used to just arrive at the airport and book something but am not sure now because of Covid and Songkran. 
 

Any way to book online? 
 

And for Koh Samui, do I need to rent a car (which probably will be too late anyway)? 
 

[Tropicalevo]

Cannot tell from your post if you plan to stay on Samui or just passing through to KPN.

Foot passengers from Samui to KPN can book with Lomprayah (speedboat) at

https://lomprayah.com/timetable

Car hire on Samui is almost non existent for this Songkran holiday.

You could hire a car at Suratthani and drive to Donsak (Seatran or Raja). Definitely book the car ferry.

https://www.seatranferry.com/

https://www.rajaferryport.com/?act=p&title=sailing-schedule

You could even take a car to KPN from Samui via Raja. Nathon to Thong Sala