Upvote:2
Depends on when you are going. Koh Phi Phi doesn't have lots of accommodation and during peak season everything will likely be full. And unfortunately, if there is no room at the inn, it means arranging a boat ride off the island to search elsewhere.
Now a days, most lodging establishments in Thailand have a website or Facebook page. So if you are not find anything I might consider either a daytrip or another destination.