I write to advise of an excellent place to stay on Koh Lanta island called Atcha Pony Hut.
Its basically a small hippy / alternative style farm that is 5 minutes moped ride to Klong Nin beach. There are numerous animals including horses, 12 cats, goats etc. They are living a sustainable life by doing pony riding for tourists and selling amazing handmade 'spiritual' jewelry. They also have a small coffee shop and make the best iced coffee (thai style) that I've ever had!
If you agree to work for them on a daily basis they will provide free accommodation in either tent or bungalow. They are very cool people and not controlling in any way. You can decide if you want to work with the animals, in the garden or help build a bungalow and there are no rules as to how many hours work per day. If your helping out then they will also feed you lunch and dinner and she is an amazing cook.
Check out the website
http://www.atchaponyhut.com/