do I need to do well in the mocks?

Heyy, M25 here! Well, my mocks are starting this Monday, and it is safe to say I am screwed! I tried to study these past two months, but I still feel like I am going to do horribly. I tried my hand at a few past papers this week and realized I still have a lot to go over, but no time at all to do so.

I plan on going to university abroad (most likely in the US, Canada or Europe), and know that some unis have early applications that may require my predicted IB grades. So what I want to know is: what's the real value of my mocks' scores? Should I kill myself studying for them in the next three days or just focus on my IAs and EE?