there is nothing too complex here; I got the clock from this link
https://github.com/Engineeringradio/pirsclockfull
The PI is overclocked to 950 MHz and set to always output audio on the 3.5mm jack (not the HDMI). The clock has to run as root for some reason; I've set up the PI to allow SSH connections (only from the internal network) and can access it from any other computer - so I open up another terminal session and run VLC from the command line.
It does cane the CPU doing both these tasks and I'm not even sure how to add Python code to check if the audio is there so I plan to build an analogue silence detector as I've got an alarm autodialler I could hook up to it (there is an entire telephone exchange in my house and a GSM terminal adapter; I build things like this for work...)