This course requires either Biology 2A03 or Kin 2Y03/2YY3. I am planning on taking Kin 2Y03/2YY3 this year, does anyone know if they will allow me to take Biology 3U03 so long as I am taking the required Kin courses at the same time?

I think you may need to talk to your department and get a waiver so they'll let you add Bio3U03. I was in a similar situation, and they made me wait until September to add the course since I didn't have my prerequisites "completed" yet, although I'd be taking them in the same term.