The project has continued, held back a little by holidays and work, but we're reaching the end now.
The electronics are working so now I just have to make them more permanent and take away the prototyping breadboard. There's a simple calibration interface, so if there's a power cut and the clock needs to be reset back to its initial position I can do that with the press of a button. I still need to mount the buttons and a warning LED into the case.
However, a trial run today worked very well, and the app seems to be functioning perfectly.