Sorry I know more about jewellery than I know about Latex but I get a lot of questions regarding where to go for this.
ionatural is in Phuket - an interesting site with some information
Royalatexphuket - was the first I got on return to a google but they are in Pattaya?
So Wikipedia it is
There are a number of places on the island who will deliver to your hotel - but I saw a sign in the local village that they have them for sale there now.
Does anyone believe in Latex?