Since you passed 12th with PCB and now want to enter BTech CSE, the safer and better option is to take the university provided bridge course in Mathematics, even if it is UGC approved and not AICTE. Many universities admit PCB students into engineering through such bridge courses, and it is legally valid as long as the university is recognized by UGC. On the other hand, going for NWAC and getting a fresh mark list with Mathematics may create issues during verification, as some states and institutions do not fully recognize it for professional courses. So, the bridge course route is more reliable, safer, and widely accepted.

Since you have a PCB background and want B.Tech CSE, the bridge course is convenient and lets you start immediately, but being only UGC-approved (not AICTE), it may cause issues for higher studies or certain jobs. The NWAC board gives a full mathematics marksheet, which is universally recognized and safer for future exams, higher studies, or switching colleges. So, for long-term security and recognition, NWAC is the better option, though it may take a bit more time. The bridge course is easier short-term, but NWAC is safer long-term.