Submitted my return with my common law partner (student and didn't pay taxes). Didn't give me an option to enter his T4 details. Does he need to submit a separate return?

It sounds like you might not have prepared your returns together at the same time in TurboTax. If you had, TurboTax would have prompted you to enter both your and your partner's income amounts. And when you reached the filing section, would have been prompted to print or NETFILE twice, once for each of you.

If you didn't get the option to file for both you, then yes, your partner still needs to prepare and file his return.