Just thought I would loop back on this. I managed to get it working. It was a silly mistake on my behalf, when I read the tutorial for the component over at Sparkfun I didn't pay attention to the line ending quirk when you switch into command mode. Anyway - all good now.
In the end I didn't pick up a TTY-USB adapter and instead used the Arduino Serial Monitor and a small sketch to shunt the data backwards and forwards. Thanks for your help!