I think I will need to apply for an irregular offer... Don't think I will get the ENTER for my course 
This sounds like a misunderstanding of the system. Why wouldn't you just assign a 'safety net' course lower in your preferences? For example, I set Science at Monash as my 8th (lowest for me) preference, just in case I got some really low ENTER.
You can still aim to get 95+ for some difficult course, fail to get 95+, then get your next preference. Irregular offers are for people who did not get any offer due to
all of their preferences requiring too high scores, or because they wish to relinquish their current offer for another course they either did not previously consider, or one they ranked with a lower preference (i.e.: you get a Medicine offer 1st preference, and then realise you want to do Commerce 2nd preference - or perhaps it wasn't on your preferences at all!)
Anyway, there is change of preference week for any preference tweaks that may be required after you get your results.