That schematic looks good to me, however I would decrease the 10K resistor to 1K. For current measurement, I suggest a Hall current sensor such as http://uk.farnell.com/allegro-microsystems/acs712elctr-20a-t/sensor-current-20a-soic8-712/dp/1329624. Alternatively, use an axial leaded resistor of about 0.02 ohm such as http://uk.farnell.com/vishay-dale/lvr05r0200fe73/resistor-precision-0-02-ohm-1/dp/1108083 and an op amp. The trick to getting good accuracy with a low value resistor is to solder separate sense wires on to the resistor leads, between the resistor body and where you connect the power. The sense wires feed the op amp. That way, the resistance of the connections doesn't affect the accuracy.