I got it from Superdrug for 99p. 'Pure Coconut Oil', beside the shampoos.
The first time i put it in i put a tiny bit too much in and it went hard, but i just rinsed with cold water and it was fine.
I guess it probably wouldn't work as well for people with naturally greasy hair... as it might just make it look too oily. For really dry hair though it works a treat- as long as you dont put too much on, as BunnyWabbit says.
I wouldnt suggest putting it in the microwave, it melts on contact with your skin so no need really. :)
From what I understand it smoothes out the core of your hair or something, so it will help with heat damage- i still use my heat protection spray though.