Oooh that's old. I doubt that you will find an electronic version of the instructions. It is basically a timeswitch that allows you to have just the hot water on (Summer) or the hot water and central heating on (Winter)
The slider switch on the left hand side is the key. Move it to the right and hot water and central heating will come on. To the left, hot water only. If the pipework is as old as the programmer, it may possibly have a gravity hot water system, whereby the hot water cylinder is heated by by gravity flow from the boiler (as opposed to the usual pumped method) If so, it will be very slow to heat the hot water.
The top right button where the text is missing should say "Select" this moves the display pointer from: off / twice / once / on. (at the moment it is set to 'on' so it will be permanently on) The top left button should say "Advance" this advances the programmer on one step, should you want to turn it on (or off) before its set time.
