Which hotel / clinic?
Most hotels have room service which you will need the first week you have the catheter. Nurses should also be visiting daily. Make sure your room has internet and a working tv and just relax. Once you are allowed out of the room it is really good to go for breakfasts and meals (if you are comfortable enough) as hotel staff will always talk with you. And you might get to meet other guests. Just be polite and friendly.
Before you go Into the clinic make sure you stock up on water and powdered rehydration salts. Biscuits and snacks (once off the liquid only diet). And organise your room so that it is easy to move around / find things / visit bathroom to empty catheter.
Sind Sie Deutscherin? Die Hauptsprache im Thailand sind English. Seien English ist genug für Einverständnis mit dem Leute im Hotel und Klinik. Ich wäre bei Dusit / Chettawut im Lezte Juli, und hat geschreibung Info hier im Forum.