if your good with gaugeing strength here is a way of working out torque without a wrench.
if you need to tighten 10Nm - this works out as the pulling force of pulling 1Kg over a meter
40Nm = 4Kg over a meter, and when it starts to get harder your at the torque.
this is not advised but good if you dont have a torque wrench!
or get yourself down to argos i picked up a torque wrench for £20 FTW