Hi,
The nearest decompression chamber to koh tao is actually on koh samui so getting to that isn’t a problem. I did my padi open water on koh tao which was ok and saw a fair bit but then went down to the perhentian islands in ne Malaysia to do my advanced open water which was amazing. Even just the snorkeling around the islands was incredible. Would highly recommend it, I went with matahari dive school on the small island.
The open water course was 4 or 5 days and the advanced was about the same.
It may be worth checking with dive schools if there are any restrictions on what you can do within that sort of timeframe post op.
Hope that helps
Doug