To make travel plans to reach Koh Phan Ngan it really depends on which part of Thailand you're travelling from. The closest islands to Koh Phan Ngan are Koh Samui and Koh Tao – from each of these islands you can catch an inexpensive ferry ride. These operate throughout most of the day, from the ferry its most likely that you should be able to walk up to the beach. If you're travelling from Bangkok – the easiest option for you would be to get on a flight to Koh Samui and take the ferry from there. However there are also overnight bus and train options available also, you will probably have to use one of the other if you're coming towards Koh Phan Ngan from any other part of Thailand apart from the nearby island or Bangkok.