Can you give me idea what it's like? Like stuff people should know prior too doing this course?
You should prepare yourself by studying a bit of C (unless they have changed it, which I doubt). The first few weeks are easy, but it then increases in difficulty considerably, IMO. You make programs which deal with logic, e.g. multiply a number by 3 if it's even, reduce by 10 if its odd, print out the series of numbers; or count how many A's are in the computer dictionary without using programming hacks. You also might need to make a game; when I did COMP1917, we had to make Settlers of Catan. It's a group project, and it was fairly challenging. I don't think anyone had an error-proof game, not even the lecturer's.
But if you're intending on doing Actuarial Studies, then I wouldn't bother with 1917 because it won't be credited to your degree, so I guess it's good if you do well, but it won't mean anything in uni, academically.