The international licence only lasts for 3 months then you are driving illegally. I've just got my Thai drivers license which was a full day, I watched 4 hours video 🙈 and had some basic reaction tests. Cost was 205 baht and I'm fully legal now.
I'm a gym addict and started out my hotel search with this as the most important aspect. I soon realised it ain't gonna happen so have set myself up in the room with bands etc in order to at least do something. Expect to be stuck in your room for the duration and anything else as an unexpected surprise. That way you won't be disappointed.