I draw a schematic
For safety reasons, you can use a key operated switch connected in series with the relay contact.
I would place the key switch in the 12V line at the battery so all of the circuit is isolated until needed.
Also add a fuse.
Tom... 
What size?
You mean the sort you can ignite with a match, or cigarette lighter?
you can also sense current flowing with a hall sensor. some turns of a wire around it will detect and measure current flow...
And when current is detected id just have to write some code that lights up an LED for it?
So in this schematic, when the switch is pressed current would flow to the igniter enabling the LED?
Correct but it's only around 16mA (0.016A), not enough to cause the ignitor to fire.
Alright okay.. So the LEDS ground terminal is connected to the nrormally closed pin of the relay, and the switch is connected directly to the battery?
The LED and resistor are connected across NO and C
Right but this in this schematic the LED would just switch on when relay is clicked regardless of whether the igniter is connected or not
Does that schematic represent you current set-up?
I assuming you are using a 12V battery and a SPDT relay, one that has three connectins. a common, NO and NC.
Will use a 9v battery on a 5v relay module, and a relay module, not a plain relay..
can you give a web link to the relay module you are using
ITs a 2 channel, 5v relay module.
Does this make more sense?
Yes, however the battery would have to be connected to the jd-vcc or vcc ports on the module to power the relay and to use it accordingly.
It's a 5V relay so it needs 5V not 9V
If you only use one relay, then you can connect it the Uno 5V pin