With law/commerce, its not exactly double the work of a standard degree, its just a bit extra. For most of your degree, you will overload (i.e. one unit more a semester than a standard degree). Also, with law/commerce, you will be required to do less units, because some of them cross over into both degrees (like business law). Overall, the workload for law/commerce isnt too intense and its manageable if your motivated and have a decent work ethic. Be sure to let me know how you go with your preferences when they are released in January.