I looked again at what would be a useful addition and decided to add a 3.5mm jack socket for the audio input.
I decided to use the PJ320A which seems to be readily available from Amazon, e-bay, aliexpress etc.
I purchased 15 for £5.49:
https://www.amazon.co.uk/gp/product/...?ie=UTF8&psc=1
I had to create the footprint though.
Images of the front and back attached
Peter