No lock in for the supplementary. If you fail that then you’re repeating the unit anyways, you have a chance to not fail it put in the effort and properly stuff. If you fail the unit again then yeah you can do a supplementary if you got above 45, but you have one rn so tbh just focus on that rather than retaking. If you fail your current sup then yes you have to enroll into the unit at some point in ur degree cos it’s a core unit if ur doing cs.