The thing about the after-mission sims is that their mainly there for us to squeeze a bit more fun out of the remaining time. So if you’re adamant about not swapping stations, especially as an ensign, I don’t think anyone would make you.
However, it would be a fantastic chance to learn more in a (mostly) stress-free environment. More so when the rest of the crew is learning right alongside you.
What I’d recommend for you as a Weapons officer is to give either Science or Helm a try, as both roles benefit from having tactical experience. You may want to avoid engineering for the time being. Knowing the other roles is rather important before tackling that beast.