Hi there,
When you apply for Undergraduate Law (LLB) at UTS, it is done through the UAC. Depending on how long you have studied in your current undergraduate, they will most likely look at your university grades and possibly on your UAI. Your marks will be combined to give you a rank where you will compete against all other applicants (I.e. Current school leavers and Non-Current school leavers). The top ranking students within the admissions quota will be offered a position. I don't think it's as simple as adding the two marks together and giving you an average, but I could be wrong.
So technically, you wouldn't be 'externally transferring' into the LLB. You'd be applying for a new course. You will however, be eligible for Recognition of Prior Learning as the LLB has 48 credit points worth of unspecified electives (that is if the subjects you have completed in your undergraduate are of equivalent weighting to what's offered at UTS). If you are considering completing your undergraduate degree, you may wish to take into consideration the Juris Doctor (Postgraduate version of the J.D). It is actually less competitive to be admitted to the J.D as it is a postgraduate full fee paying course. Although, if you're a PR or Aus Citizen, you'd be eligible for FEE-HELP.
Hope this helps. =)