Hello Heid,
Yes the Thailand Audax rides are quite good.
Once you have registered and received your official Audax member number you are free to sign up for any 200km ride. Once you have completed a 200km you will be allowed to sign up for a ride of 300km distance, and so on.
Great article explaining all of this can be found here - http://bicyclethaila...me-to-thailand/
Sign up for the upcoming Rayong ride on the Audax Thailand website where it says Registration and pay the required fee (200 THB). Once you do that your name will appear on the Participant List.
Start time for the January 16th Audax is 7:00 am so you should arrive earlier than that by at least 45 minutes.
You can download the entire route (including start and end point locations) from the website in CueSheet, Strava, or GPS formats (like .gpx and .tcx). Some type of GPS unit is highly recommended and will make your 200km trip much less stressful, especially if you're not great at directions.
Hope this helps.
Enjoy!