If in the event you do fail, and it is a core subject for your program, then you must redo the subject.
If MATH1151 is a prerequisite for another subject (e.g. MATH1251), then you can't do the other subject until you have passed MATH1151.
Assuming you pass all your other subjects, you will be on 18UOC of completed credits. This will mean your enrolment is put back to a later date, compared to those who would have completed 24UOC. (this will really apply for next year, because you have already chosen next semester's subjects).
There is a possibility that you may need to spend an extra semester at uni, or a summer semester. You will most likely not be allowed to overload since that generally requires a certain WAM, but you may be in the position where you have done extremely well in your other subjects so your WAM is still high enough even with a fail.