I'll be making a trip through Thailand and I only have 18 days. I already booked a flight to Chiang Mai and a flight from Bangkok back home. I'm also going to book a flight from Bangkok to Ko Samui and back to Bangkok right before my flight back home. I haven't booked the flight to Ko Samui yet because I'm not sure how long I will stay in Chiang Mai and in Bangkok, so I don't know the date yet. I know there are a lot of flights between Bangkok and Ko Samui, so...
Is it possible and advised to just go to the airport in Bangkok and buy a ticket there to fly to Ko Samui already a few hours later (and the same for returning)? Or would you discourage to do this and advise me to just pick a date of departure and book this flight already?
Some advice?