Sorry to bring this up again but I overlooked the buying of the resistors. Turns out my source of resistors didn't have any 1.2 ohms or anything that could be used to make a 0.4 ohm total.
I went looking on Farnell and RS but I'm now not sure of the number of Watts I'll be dissipating across each resistor. This is regarding the 3 1.2 ohm resistors in parallel. The 100 ohm MOSFET resistor power is tiny and not a problem.
Using 10A and 4V I came to 13.3W per resistor, but this seems rather high and any resistor with this kind of rating seems way too big for what I'm doing. I mean most of them have heat sinks attached and look like they should be controlling something 10x the size of my motors.
Have I made some silly mistake with the 13.3W or is this correct? If so, am I just failing at finding resistors?
Thanks a lot, once more 