If I were to not be able to finish an assignment today, or if I fail this assignment for my first attempt, would I be forced to leave campus and go back to my home country?
Well, it turns out that I will have until next Tuesday to finish the wee assignment. So, thank you so much for all your help. I am still very safe in the program.
Thank you so much. May I ask what you mean by withdrawal for failure?
Expulsion is generally where you've committed misconduct. (This might be "traditional" misconduct, for example physically assaulting someone; or academic misconduct, for example, cheating in exams.)
If you fail exams, coursework, etc, then you would normally be given the chance to do a resit of exams, or a re-submission of coursework. Unless there are extenuating/mitigating circumstances, the resit/re-submission is for a capped mark.
If you fail the reassessments, you'll ultimately not be allowed to continue with the course. Universities sometimes use the phrase "required to withdraw" (or similar) from the course, and I assume that's what @gjd800 means by "withdrawal for failure" -- presumably that's the phrase used where he/she works.