I don't play an instrument, but with being into sound production I can say knowing general music theory helps a lot.
It doesn't have to be anything crazy like knowing how to read sheet music, just things like understanding bars, octaves, note types, etc can go a long way.
This all should come naturally when learning an instrument though, but without a physical teacher I can more or less guarantee it will be very hard to learn.
If you can't afford one, make use of free resources such as YouTube. I'm sure there's tons of videos and other sources out there for you.
Good luck!