Emma Roberts Says Playing Britney Spears Would Be 'True Dream'

Emma Roberts is ready to embrace her "Toxic" side ... saying she's ready to jump in Britney Spears' shoes -- and, she's even practicing her songs in front of an audience.

The actress sat down for a wide-ranging interview with Cosmopolitan ... and, the star talked Britney's former personal assistant, Felicia Culotta, telling us Roberts would play the perfect Queen of Pop.

Emma says playing Britney would be a "true dream" ... and, it's certainly a rumor she hopes will come true.

In fact, Emma admits she's a huge Britney fan ... saying she locked herself in her room when her 2003 album "In the Zone" came out -- swearing she wouldn't let herself leave until she knew every song by heart.

Emma adds she's actually practicing the songs in her day-to-day too ... singing them for her son during bathtime in a classic "millennial parenting" move as she puts it.

Britney seems less sure about casting at this point ... posting on her Instagram Story asking fans what they want to see in the upcoming film -- so, obviously the movie's still in earlier stages.

Of course, fans have been calling for a Britney Spears flick ever since her autobiography "The Woman in Me" came out last fall ... with many wondering who might play Brit and some key people in her life, like Justin Timberlake.