can only find alliance code for full set for casual wear can't have it as armour...
This is a false assumption. You can add these armor pieces and use them in combat as long as you also assign armor bonuses to them (+5% Shields, for example) and put them in the appropriate place in your Coalesced.bin. It's all explained in that blog quite clearly. It does take a bit of time to go through because there's a lot of information, but it's the only way to do what you want.
For example, that heavy Alliance armor, you would go to BioGame.ini, SFXGame, SFXPlayerCustomization, TorsoAppearances, and on the right column you would go to whatever blank line is available (or add a new one) and put in the following code:
Note that the power damage bonus is just there for this example. You can change that to any other bonus or even give the armor ALL the bonuses. Whatever you want. Anyway, once you've done that, you just save the file, fire up the game and then go into the armory (shuttle bay or the cabin) and browse the torso armors -- that's the chest pieces. Your new armor should appear there, ready for combat.
Going back to the "it can only be used as a casual appearance" -- if you know the model for a casual appearance, even those can be used in combat if you add them into the TorsoAppearances section and give them armor bonuses. Want femShep to wear a skirt into battle? Go for it. It can be done, you just need to read that blog and learn how. It might seem overwhelming at first, but once you've done it a few times, it's really pretty easy to do.
Don't give up.
EDIT: Just wanted to add a quick note here. I was assuming you had an editor ready to go, but since you're obviously new to modding, it occurs to me you probably don't have one. You can grab an easy-to-use Coalesced editor here: http://wenchy.net/me...lesced-utility/ - This is required to open your Coalesced.bin and edit it without corrupting the file.