assist.org will give you the classes you need to complete the lower division requirements at different UCs. Make sure you read it carefully, since some classes are REQUIRED and others RECOMMENDED. Also, it may list a ton of classes, but only say you need 1 or 2 of the ones listed.
IGETC is the equivalent of General Education at the UC level. It is not required, but it can be helpful to clear your GE requirements and allow you to start taking upper division courses right away.
TAG uses major requirements, a certain amount of units, and GPA. Will you have 30 units COMPLETE (not including in progress) and a 3.4 by September?
Here are some useful links:
assist: http://web2.assist.org/web-assist/prompt.do?ia=UCI&ay=15-16
IGETC: http://admission.universityofcalifornia.edu/glossary/igetc.html
http://admission.universityofcalifornia.edu/transfer/general-education-igetc/igetc/
TAG: http://admission.universityofcalifornia.edu/counselors/files/tag-matrix.pdf
UCI TAG: http://www.admissions.uci.edu/applicants/tag.html
Edit: Also, a good thing to keep in mind when planning courses is Major Prep > IGETC