Generally 3.5 is a probably a good enough GPA to get you interviews in places of high demand e.g. Big 4 and Investment Banks. GPA and cover letters/resumes are the 1st screening process - so have a good cover letter and resume (even if you have GPA 4.0 but still crap cover letter, then you're gooone.)
A lot of Actuarials go to Investment Banks (you basically need to be super smart, have v. good extra cirrcular activities, be a great talker and be extremely knowledgable and up-to-date on the investments scene i.e. read the AFR regularly - either that or know someone in IB). A lot of my friends stuffed their IB interviews because they got asked questions about the investment industry like 'Whats the average IPO for the industry now', 'Whats Black-Scholes formula' - you can't really bs your way through in IB because its what you know, not how you sell yourself.
You DON"T need some super high GPA to get you jobs (it's just easier to get interviews if you do have one). I'd imagine a lot of the smaller firms will give you a shot if you're a Cr average.
If you don't, then you might end up in some other finance - non-actuarial role, like financial management or something. Then when you get fully qualified, you can just jump ship.
Most Macq grads get employed somewhere anyway - according to statistics.
EDIT: When you've grad, noone cares about your marks - its how well you perform and whether or not you're fully qualified - being fully-qualified is the important thing.