Thanks for all the responses!
Regarding what I'm trying to achieve:
Currently in my application using Csound, I send ready made instrument definitions and scores to Csound and just make it play that. Nothing really complicated by the time I get there. The only extras are stopping, pausing, and receiving callbacks both at the end of score and at the end of sound being produced (for reverb tails and the like). I'm happy to modify my methods a bit to get supercollider working with my app, it doesn't have to be like that, that's just how I found works best with Csound.
@nathan that sounds interesting, I might need to ask questions when I try that, I struggled to build SC normally from the instructions. I'll look into what I can achieve with OSC, but I suspect it won't be exactly when I'm after.
@asm, that MIT book sounds like it's worth a look. This one?
@wondersluyter, I'll check that out, if someone's done similar it before then it can't be totally out of my reach