Y1 without a teacher was a big challenge. Like learning a new language you want to get pass "absolute beginner". Today people rely on the Internet for learning. In my younger days couldn't imagine using a book to learn piano on my own. The transition from self-learner to having a teacher doesn't have to be painful. As long as you spend a lot of time learning from online sources, track your progress, make recordings regularly.
After watching student performances you know many of the pieces a student would learn at specific levels such as the beginning of Beethoven "Fur Elise", mvt 1 of the "Moonlight Sonata", "Minuet in G" from the Notebook for Anna M. Bach, Bach Prelude in C from WTC-1, etc. When you're still playing out of Alfred's or Faber 1 & 2 you have expectations the pieces you'd be learning eventually.
In my school days learning violin was a nightmare. The teacher would point out specific problems. By the next lesson a week later the same problems would come up. Today a lot has changed. Many of the pieces a student would play are already online so can't say you haven't heard a piece before. Unless you intentionallty avoid doing a Google search. I'd use a phone to record the teacher's playing during a lesson so I know roughly her tempo. When she pointed out something, I'd make a note and have it fixed by the next lesson.
Nobody expects you to play perfectly the first time. Without a teacher you don't realize what you're good at and what you still need to work on. It's not a big shock being told you have 10 things to work on. It becomes an issue if you come back with the same problems in the next lesson.
Having a teacher is a good idea. There are a lot that aren't written into the sheet music like playing a trill the Baroque way you'd start on the higher note sort of thing. Just following the score you play all the right notes but can sound better based on specific styles of music.