Trying to help, but having a hard time coming up with an equivalent expression (although it seems to me there is one, I just can't think of it right now)
I suggest changing the sentence around to say:
"Without this information, I will not be able to move forward with my studies".
"It is imperative that I receive this information as I cannot (or 'will not be permitted to') continue my studies without it"
Depending on the formality and/or purpose of your letter, you could say that it is a "showstopper." This has been a recent "buzz word" at my work to refer to something that keeps us from moving forward on projects.
'Bottleneck' is the usual transltion of 'goulot d'étranglement', I think (and 'stumbling block' is 'pierre d'achoppement'). While I Rocket Girl's proposals, I think "This [information] is a sine qua non for me to advance in/to continue..." // "Cet enseignement est un sine qua non..." could work. or "This (piece of) information is indispensible if I am to continue..." // "L'enseignement manquant est indispensable pour me permettre d'avancer dans..." It seems to me that "mon étude" is a project, not "my studies".
(But was the OP asking for FR or EN??)