I am running a test on the Blitz datascan, what sould the reading be on tickover 750rpm. The screen is showing 10 on the scale and only moves slightly when revved. Is this only one side of the o2 system ?

The readings below 2000rpm are irrelevent, the system runs a closed loop system. You need to hold the revs at 2k+, and both o2 sensors readings should switch from lean to rich continously.

On the screen it only shows one sensor, which one is that ?

Left hand. You can turn on the other sensor in the settings (listed as o2 Sensor RH), you need to replace one of the other shown sensors with it.

Done that, what reading should I see on a healthy sensor at 2000rpm?