Sorry Thwarptide, but this is not really the best advice.
If you submit to an interdiction from a mission spawned NPC and then go back to SC the NPC will simply spawn again right behind you seconds later and will interdict you again. You need to either evade the interdiction in which case the NPC will be gone, or you need to destroy the NPC otherwise you will continue to be interdicted time after time.
If you submit and jump to another system the NPC won't follow you, but if you still need to complete the mission that doesn't really help you. (Also, there's no mass lock in SC only in normal space. You can escape an interdictor by accelerating away from them in SC, but they will catch you when you decelerate to drop out at a station.)
@ArcherS , yes, it's a bit strange that players can take missions way higher than their rank and experience, but that's how FD decided to do it. It wasn't like that early in the game. And of course those missions pay more, so players want to take them, hence we get threads like yours wondering what happened to you!. Best thing you can do is to pay attention to the mission rank as that will determine the challenge that you may face.