The current political situation is uncertain in the politics world however on the surface it appears to be settled. Therefore, for your situation, the political situation will probably not affect you too much.

Late May to November is Monsoon season in Phuket however the rains are usually short and hard. It is a good time to avoid the crowds and have a chance to talk with the locals. The High season is November to March and that is when the weather is mild and pleasant.

when were you planning on going? this website may be useful: http://www.phuket-guide.net/phuket_home/index.htm

I wouldn't worry too much about the political situation. Foreigners don't get affected too much.