See http://admissions.sa.ucsb.edu/applying/transfer/tag and also the tag matrix pdf at http://admission.universityofcalifornia.edu/transfer/guarantee/ which shows required gpa
If your counselor doesn’t have much info about TAG, find another counselor. Helping students xfer to a 4-year college is what they are paid to do, it is inexcusable not to know such basic stuff. This is especially disappointing since Diablo is the 4th largest source of UC transfers to UC according to http://www.latimes.com/local/education/la-me-uc-transfers-20140515-story.html Drop this lemon and find someone better!
UC counselors visit Diablo regularly. It doesn’t look like UCSB is coming soon, but meet with a rep from any UC that has TAG and they should be able to help you out. See http://www.dvc.edu/enrollment/transfer/reps-visit.html#UC
“-will apply to UCSB as a transfer from DVC by end of next year or fall 2017” Not sure what you mean by that; UCs only accept apps for xfer in Fall to enroll at UC the following Fall.