omg hiiiii!!! sorry i just saw this now!!! i went to a language school (i’ll happily send all the info abt it in dm if you would like ^^)! i think you’d be fine starting from scratch in most schools (though you should inquire and make sure,, don’t take my word for it), in my school they made everyone take an evaluative test on the first day and then sorted us in the right class for our needs/skill level!! there were plenty of people starting from zero (hiragana and katakana/my name is etc) so don’t worry about it too much (though i would recommend learning at least hiragana and katakana beforehand), in general my school was very flexible and would move students up/down a level at the end of each week (if it was needed ofc), for example i was placed in pre-intermediate on my first week and then they promptly moved me up when they noticed i had it too easy/it was covering things i was already familiar with, so i’d make sure to look for schools with this method!! a friend of mine went to a school in kyoto where the levels were much more rigid and she ended up not learning a lot bc it wasn’t the right fit for her!