There are also many international students who study law and do well. I agree with brenden; how well you go in your degree will be a product of the time and effort that you put into your study when you have to, not a reflection of your past performance in high school English. Besides, a 39 is still a pretty great score - you reside in the top ~10% of the state, and the fact that you have the ATAR to get into comm/law in the first place indicates that you may have just had a bad day on the English exam, but done well enough everywhere else to secure a place. If it's what you want to study and you meet the prerequisites, don't let that stop you.
Personal anecdote: I'm doing biomed at the moment despite not having done VCE bio and the two prereqs (methods/chem) being my bottom two scores. I try not to let this get in the way of enjoying the degree, and you're definitely in a position where it won't be a problem.
Best of luck and have a nice day.