Take a bus towards Surathani (or you can catch the first bus north to Takua Pa, where you can transfer to a Surathani bus). About 35-45 minutes after leaving Takua Pa, the bus will pass the junction for Khao Sok National Park - get off there at the Khao Sok bus stop.
From there, tell one of the pick-up truck drivers to deliver you to Our Jungle House. This should cost no more than 50 baht per person. For more information, click here.
DRIVING KHAO LAK TO KHAO SOK
Drive north to Takuapa on Highway 4, and then east on Highway 401 (towards Surathani).
Google Map Khao Lak Khao Sok, click here.