@Lewis **********
Your Thailand Pass is for entry into Bangkok. If you don't enter Bangkok, you need a new Thailand Pass for Phuket. If you changed something like your hotel, it would probably be fine to just carry the new booking with you, but that big of a change will not be allowed under the same Thailand Pass. The airline probably wouldn't even let you board, and even if they did you run a huge risk of being refused entry to Thailand. Someone was refused entry recently for arriving 5 hours too early.