Vadim,
Do a check on the forum, similar question was raised and aswered some 1 month ago. If you want freediving training/fun, you will find one center located in Koh Tao, a splendid island close to Koh Samui, off the eastcoast. Amazing diving/freediving can be done on the west coast too, with Pukhet being the main base. I havent done freediving on Similan islands, off Pukhet, but it's a fantastic place with good depths for freediving and amazing wildlife.
serge
PS might be there in December too, in Koh Tao to swim with black tips
