Reading progress update: I've read 110 out of 512 pages.

Nonlinear Dynamics and Chaos: With Applications to Physics, Biology, Chemistry, and Engineering - Steven H. Strogatz

I had to start over from the beginning but I still think it's an excellent book. Up to this point it's also fairly easy, requiring only A-level maths. It's going to get harder shortly when we progress from one to two dimensional problems, I expect.