Hello! After admiring Angie's outfits and the classic looks of Audrey Hepburn, I decided that I really would like a white oxford shirt. However, I'm having a hard time finding shirt that is:

• long enough to tuck in
• in thick cotton material
• that is not embellished

Where do you ladies shop for such a shirt?

Also, a weird question: are you supposed to wear a camisole under a button-up shirt?

Thank you!