So, I've just started singing in a choir and I'm absolutely loving it. However, having never learned an instrument (and pretty much ignored whatever music lessons I had at school), my knowledge of music theory is very basic. I can read music at a rudimentary level (basic notes, rhythm and notation), but it's all just stuff that I've randomly picked up. I would really like to go back to the beginning and start to understand music theory properly. It occurs to me that there must be good apps or books that I could use, but when I've had a Google there's so much out there, I don't know where to start! Can anyone point me in the right direction?