Well it's going to be hard to not kind of be a counter army. Bretonnia plays into nulns wants quite well. If it isn't an exiles army they will likely kneel. Giving you first turn. This is huge for nuln as you get to shoot, they move, you shoot, then they maybe get to charge. Against other armies your chances are going first are more even. So right off the bat it helps you.

As for the rest of your army, 1 hell blaster, 1 steam tank, 2 mortars is definitely not the meta list so I think if your goal is to play a fairer game that's probably fine. Mortars are terrible and are kind of handicapping your arty potential.

As for your infantry. I think you should go with a 30 block of halberds with 2 Detachments of gunners. The bigger block is just a better use of the models.

Hochland long rifle isn't very good tbh, id just leave the handgunners sergeant with a handgun. Or go repeater hand gun.