Hi Calv,
Thanks for all the tips. Bit late though.
I've not updated my post since the other day as I have been busy with the code.
I now have a fully working system.
The master unit has all the menus and modes. I did use an array as you suggested above. I had to use debounce and edge detection for the button presses.
The slave receives the program number from the master then takes care of itself.
So there is only a couple of bytes of data to send. I can have feedback but don't really need it.
I'll do some pictures and maybe a video later and post up the code for you to look at.
The next stage is to do a couple of boxes and get the servos mounted on a frame. Then cobble together some wire frame target holders.
Many Thanks
Mark