Hey, just wanted to give you some advice about your choice of liveaboard! In April, I went on a liveaboard to the Similan Islands with Sea Dragon Dive Centre in Khao Lak and it was phenomenal!
This is their website: http://www.seadragondivecenter.com/
Unfortunately, it doesn't seem like they schedule any liveaboard trips in early October, season starts in November.
But if you're going to do a liveaboard, I really recommend them - I had a blast with the divemasters, it was incredibly well organised and professional and a really great experience!
It may be worth writing to them to see if they have any daytrips scheduled in October?
Good luck!