Ah, the "Real Book," that final arbiter of musical truth and beauty . . .
Kitsch, close the book. You want to get Sonny Rollins'
Saxophone Colussus. It is generally recognized as a "desert island disc," one of those few which are required in a complete study of jazz music.
Study Doug Watkins' line over and over, hard. The melody, Mr. Rollins' all-time-classic solo and Mr. Watkins' line are all intentionally ambiguous as to whether the tune is Bb or E blues. (It's not THAT ambiguous and eventually settles into Bb.)
For your high school ensemble, if you just play a regular Bb blues you'll be fine, IF that is what the other people in your group are playing.
But don't neglect the record. It's completely, totally the real deal.
Have fun. Report back.