Hey, im currently in social science for bachelor of arts in PNB(psychology, neuroscience and
behavior) and I have plans on trying to switch into bachelor of science. I currently am doing all the classes needed to get into the program second year, except for one bio class I couldn't get a place into. I'm hoping when the academic year starts I'll be able to get myself enrolled in the class for second semester.

I was just wondering, if switching is even possible, and if it is how difficult will it be to switch, and what can I do to ensure the best chances of me getting into the program I want second year?

I was also wondering for the type of classes I will be taking, what should I expect textbook cost to be like?

If you are just in first year, you should not have a problem switching.
In first year, you're just in a general program and you're not technically in PNB yet. You'll have to apply to PNB in April. You simply need to speak with some academic advisers regarding switching from BA to BSc and possibly being added to the one bio you aren't able to get into. You may need to take a few pre-reqs before being able to do BSc, but I cannot imagine it being anything major.

I got into PNB missing one course from first year, but got special permission to take that course over the summer and I was still accepted into PNB Mental Health.

Hope this helps!!