I have a CH programmer, to set times heating and hot water, but as I never use the timed functions and leave both set to on, then wonders if a light switch ( 5amps I believe ) would be suitable for each service....
If you are installing the switches to control the same circuit that the timers turn on/off, then I see no reason why you couldn't install a manual switches to do the same thing the timers would do.
I can't any reason either, as far as I can make out a CH programmer opens closes a switch wire, don't think it's a double pole switch, so a simple light switch should do. just wasn't sure what current, if any the programmer switches.