Faking not allowed
Fake it 'til you make it?
Perhaps that works in some areas in life, but I don't suggest it in tango. Faking devolves into inauthenticity and superficiality which I believe are detectable in tango.
Yet, new tango dancers encounter the challenge that tango requires clarity of communication between the dancers: a clear lead invites the follower to respond, while a confident response clearly tells the lead how the response has happened.
The question remains: "where does this confidence come from when you are just starting out and have little idea of what you are doing?"
Tango dancers need to develop confidence in their abilities. Yet rather than thinking about this as "faking" confidence early on, consider that tango is asking you to try it out. Don't pretend that you are confident. Rather, try on the feeling of confidence and let it sink in, like new clothes.
So, rather than thinking, "I will pretend to be confident and hope my partner doesn't notice", consider an aphoristic approach: "I will create a connected embrace and move with intent."
Just like you have to practice the techniques and figures of tango, you can practice the feelings of confidence. They will ultimately develop together.
Tango is a firm and challenging mistress, but she is also patient. She wants you to try. She wants you to struggle a bit, but, ultimately, she wants you to succeed.
She won't give you her gifts quickly. No worthwhile woman ever does.