Usually corrections are indicated as needing either both examiners approval, or in the case of 'minor minor' corrections, only the internal.
It's rare the supervisor can actively block it, but they may be asked for a signature to indicate they approve the submission. It doesn't mean you can't submit if they don't; but it needs reconciling, worst case being the supervisor effectively states they don't feel the corrections have been done and can't approve the submission, but it still goes ahead (in a way, absolving them of any blame).
I'd try to resolve/understand the supervisor situation, since it might be the case there's a real problem they're trying to alert you on. If it's a more awful case (like they're delaying the submission because they need a warm body to push buttons on a machine for 6 months), I'd still try to resolve it by explaining that financially you can't afford that. If you ultimately can't it's possible to submit without approval from DoS in the vast majority of programmes, but as mentioned be careful before you do as they might be trying to impress upon you a risk of a fail/MPhil.