The content for ACST101 for 1st and 2nd sem are almost the same.When I was in first sem I did ACST101 and STAT170 together, not knowing what I was heading into. Back then both units had a weekly online quiz which were not difficult but still stressful. In hindsight, although I despised those quizzes I found that they really help you stay on the ball because these are units where each week builds on the previous week. I also enjoyed doing the more easier units for semester 2, such as BBA and MTKG and ECON.
I think it's best to do ACST101 in first semester as I have heard that the actuarial students do this sub in second semester, and as such it's harder to do as well as them then if maths is not your forte. I may be wrong on this though.
The reason why actuarial students do acst101 in second semester are because mostly they overload in their second semester with ACST212.
Also semester 1 subjects only offer in semester 1. (except for econ111, but i think econ111+econ110 together is even worse if you put it in semester 2)
They have separate average for ACST101 actuarial student and non-actuarial student (around 8 and 5-6 respectively)
Basic calculation required in ACST101, achieving D or HD is very possible if you give a try even your maths is not good.
If you maths is really good, just do the basic workout can easily achieve HD (got 99 myself as an actuarial student)