What is a "Coudet Clarinet"? I'm a flute/Alto Sax player and was wonder if this is different from a "Clarinet" also how will the transition be?
Coudet is simply a brand name. Assuming you're looking at the standard Bb clarinet, the fingerings are essentially same as for the sax, with the caveat that a clarinet's "Octave" break is an octave plus a fifth rather than an octave.
As to transitioning, well every instrument has different embouchure and breath control needs.