Thank you all for your replies, your assessment of the circuit is almost accurate and perhaps even the intention of the designers. while it is true that the switch is connected across the open terminals of the relay and the board receives power when it is pressed, it only the board only receives a pulse as the relay does not switch until AFTER the mono-stable timer runs out. Because of this the sequence of events are as follows; switch pressed (must pressed until the timer triggers the circuit otherwise the board just loses power and nothing will happen) -> relay closes and the board now supplies power to itself -> relay stay on perpetually as the timer has already been triggered and there is no self resetting. The problem is that the board does not stay on until the mono-stable times out, it stays on after the mono-stable times out and only gets there if the witch is held long enough.
Unfortunately It doesn't seem like there is a way to achieve a trigger input with a single board, I have managed to solve my issues using two of these boards incorporating the normally open relay ports on one and the normally closed ports on the other.
I am still interested in this circuit and would like to experiment with the suggestion srizbf made, that is to trace the trigger port and splice a switch into it but i don't know how that would affect the rest of the circuit, now I am no expert and this seems strange to me but as far as I can tell the Trigger pin on the ne555 IC is connected to the minus side of the capacitor and what I think is the ground pin (the pin directly under the screw) of the potentiometer. Would I need to run a switch from the 12v supply to one of those nodes or what, I dont know where to go from here.