Does The London Academy of Music and Dramatic Art, Guildhall School of Music & Drama, and/or The Royal Academy of Dramatic Art require transcripts from High School by a certain date or after being admitted? Please advise 
Unlikely, these are practical courses where your highschool academic record is largely irrelevant and your audition(s) is/are the most important part of the application. (Although I see Guildhall asks for a certain GPA (only 2.5 plus SAT score of 1000 or ACT 21) so you would need to be able to prove that.) Is there something you are hoping not to bring to their attention?
No, nothing I’m trying to hide! It’s just hard being from the US. Applying to BA/BFA colleges in the states is very different than the UK. I told my college consular to send them anyway, it couldn’t hurt right? thanks for the reply!
Good luck!