Introductions are in order!

Hello everyone! Recently depression has hit me back pretty hard and in response to this I thought I'd start a narrative led 40k army in an attempt to give me back some sort of drive and motivation.

This is an Imperial crusade force charged with taking back the embattled Ishtari system which has suffered an incursion of Chaos; overrunning a dozen worlds leaving the Imperium only a single besieged agriworld in the outlying edge of the sector. The siege has lasted four years before a collection of Imperial forces have been assigned a crusade to take back this vital sector, and on the last day of the fourth year of the siege planetfall is achieved and the fight for Ishtari has truly begun.

I wanted the crusade force to represent what I envisioned an Imperial Crusade to be: a rag-tag collection of fighting men from a variety of diferent worlds fighting together loosely under one flag. To achieve this, I knew I'd have to have a multitude of worlds from which my crusade forces were recruited: I wanted my army to look impressive and unified on the tabletop whilst looking like they'd been cobbled together by a general staff swamped in information. To this end, I present to you the first unit I've cooked up:

Crusade General and Petitioners (Command Squad) 117pts

Command Squad (50pts)
-Crusade Commander Lord Shultz (Company Commander with bolt pistol and Power Fist) +17
-Crusade Staffer Leon (Veteran with Company Standard)
+15
-Major Khunart of the 14th Ishtari Trenchers (Veteran)
+0
-Leiutenant Ortil of the 6th Karlonian Armoured (Veteran with Vox)
+5
-Chem-Lord Vorshtov of the 33rd Voltok Irregulars (Veteran with Medi-pack)
+30

From this you can see the (at least) three different forces I hope to unite under the banner of the Ishtari crusade! I've put a lot of thought into the Ishtari Trencher Legion in particular when dreaming up this scheme, so I think they'll be the first models I put together/provide information on. I think I'm a little infatuated by the Tanith "Lost Homeworld" tale, but I want to avoid the hopelessness and sadness of that particular story: to that end the Ishtari Trencher Legions are the hundreds of thousands of men levied from the system to fight elsewhere drafted into the fight for their homelands.I want this force to make up the bodies of the force, and I'll be making at least one Infantry platoon of them with accompanying heavy weapons (probably mortars).

After the Ishtari Trencher Legions (yeah I like the sound of that name), it seems like my ideas get a little bit vague. I definitely want to include a group of fanatics from some sort of Cathedral planet (do they exist in canon?) with some really obscure kit, I imagine a few squads of religious zealots maybe counting as penal troops supported by maybe a manticore decked out in religious and gothic finery. The Karlonian Armoured and Voltok Irregulars exist in name only, if anyone has any thoughts/opinions I'd love to hear them!