Are your Halberdiers braced?
They shouldnt receive much if any notable damage at all from a head on charge

Are you playing Karl Franz? If not which LL did you start with?

I was playing Volkmar the grim but I have since realised that SFO is supposed to be played on ultra unit size. I've changed it and started a new campaign and I have been having some more success in battles.

I'm finding Norsca a big issue though, does anyone have any army comp tips as Empire vs Norsca?

If any unit is giving you too big of a trouble, pin them down with cavalry and shoot them with guns. :)

With Volkmar, I use halberds and flaggelants for the front line(change them into army of sigmar when you get to tier 5), and at least 1 warrior priest to buff the troops more. I like to play thematically, so I try to confed Talabecland first and get some extra Knights of the blazing sun. As empire you really need cavalry to have some mass and pin down enemy monsters and cav. Then I usually have 2 crossbows and 1 gunner(since guns are kind of micro intensive). Maybe a great cannon later on for extra tough large monsters, and that should be good.

Pistoliers can kite the boar boys very low tier unit but fast, having free company militia around too will help take down the boars, and they all forward deploy. Then you use your militia and riders to kite parts of the orc army away, the more parts broken off by a militia unit or pistolier the better, while smaller groups of orcs will attack your melee/archers/lord, who should be waiting far away on top of a hill or something. Even if you lose a couple militia in the battle, you will watch the orc army get destroyed in detail and won't believe your eyes how easy it was. Good micro practice, too. As the orcs start upgrading, you'll want to upgrade to more armor-piercing units like handgunners and outriders.

Once you get the funds, it never hurts to run two armies together. Have the second one led by anyone who buffs artillery range and then run however many units of mortar you feel like, with an ammo cart or two thrown in for extra cheese.

Works wonders in sieges as well as regular battles, just have the mortars far back enough so you can manually target enemy blobs that are fighting your front line.