@Paul: you asked ‘I need to find out if its the supply or the board I’ve plugged in the power supply onto the PI for now to check that it works.’
If you bought the power supply from us, it’s a 24VAC 750mA transformer. Can you explain what specific issue you have encountered? Is the power supply not sufficient to drive your solenoid?
Your second question is: ‘I need to run 2 systems from the OS the first is a normal retic system the second is to a float in a tank’.
DO you mean run two software systems running on the Pi, or you mean have two hardware systems (one OS, one something else)? If it’s two software systems, you should be able to run them at the same time as the operating system can multitask; if it’s two hardware systems, I will need to know what the second one.