Need advice: Accept Massey Vet Pre-Selection or wait for Australian offers?

I received an offer for the BVSc Pre-Selection program at Massey University today, and I'm feeling quite conflicted about what to do.

My first preference is to study veterinary science in Australia. I've applied to several Australian universities, but I likely won't receive my outcomes (offers or rejections) until around September. The problem is that Massey requires me to accept or decline the offer by 15 July.

I was rejected from JCU and didn't perform very well on CASPer, so I'm not very confident about my chances of receiving an Australian offer.

What makes this decision even harder is that Massey's BVSc program requires students to complete the Pre-Selection semester and then competing for entry into the Professional Phase. I'm worried about not being selected after moving to New Zealand and starting the program.

I'm also unsure whether accepting the offer and paying the fees would prevent me from changing my mind later if I receive an Australian offer.

Has anyone been in a similar situation? If you had to choose between a guaranteed place in Massey's Pre-Selection program and waiting for Australian vet school decisions, what would you do?