Can I have my photo taken at the immigration office in Bangkok, or should I prepare one beforehand?

All facilities are provided for you at Chiang Wattana Branch. Passport photo's and photocopying facilities. They even have glue there for you to stick your photo on the form. The downstairs area is fully open with banks and shops etc. Everything is there don't worry.

It want be all time in your Life good what ever you do to be prepear.

The Photoshop is open at Chiang Wattana, and I think there is one now at the alternate location in Nonthaburi, and they are cheap, but, depending on what you are doing determines how early you need to get to immigration so you aren't spending all day there waiting in the queue. By having everything ready before you get there gets you closer to the front of the queue.

My advice is to have the photos ready, I don't know if there are photo shops open, AND if there is, it'll be more expensive.