So I have a few marine models I want to compile into an army. This is what I own:
Terminator Armoured Librarian
Assault on Black Reach:
Captain with Sword and Boltgun
Dreadnaught with Multi-melta
Tactical Squad with Missile Launcher and Flamer
Terminator Squad
Battle for Macragge:
Tactical Squad with Missile Launcher and Flamer

So using these models, I've attempted to put together a 1500 point list. I found it didn't work that well trying to play to theme and fun but I gave it a shot. I'd love some advise on whether the list will work and how I can make it do so.
Previously I was going to do Raven Guard, but since I've decided that I'm going to go back to my interest in the Badab War and do one of those Chapters. Current interests are: Marines Errant (though present situation is not encouraging), Howling Griffons, Lamenters (again current situation and lack of rare gear is discouraging) and Mantis Warriors. Haven't seen IA2 thoug so I don't know what the other chapters are like in that. So...

Marines Errant:

Lieutenant Commander Anton Narvaez (Captain with Power Weapon, Bolt Pistol and Master-crafted Plasma Gun) - 135
Epistolary in Terminator Armour with Gate of Infinity and Smite - 175

5x Terminators - 200
5x Deathwatch (Sternguard) with Meltagun and Combi-plasma in Drop Pod - 170
Dreadnaught with Multi-melta in Drop pod - 140

10x Tactical Marines with Missile Launcher and Flamer - 170
10x Voidborn Elite (Tacticals with Move Through Cover and Scout) with Missile Launcher and Flamer - 170
5x Scouts with Sniper Rifles, Camo Cloaks and Missile Launcher - 100

3x Bikes with Meltabombs and 2x Meltaguns - 115

Thunderfire Cannon - 100

Total: 1475

I've been tinkering with a Howling Griffons list but with 3 HQs I really want to use (Chaplain Dreadnaugh Titus, Librarian Terminator [extensive use of Librarians] and a Command Squad with Champion and Banner) and a knight theme I'm attempting to recreate, I'm finding I'm running out of points before I create the full list and it's not really efficient

* Tacticals with Move Through Cover and Scout for free thanks to the ME character

Any feedback to let me know how to make it fun to game with would be appreciated

looks good but i will always suggest to take Combi-wepaons on sternguard and not meltaguns etc. They just work better.

Ok, Meltaguns and combi-meltas are the same points so shouldn't affect the list. Do you think the bike squad will be able to survive at all or just be shot down instantly? And don't really know much about the Thunderfire Cannon but it looks like it could be useful. I don't think upgrading the Librarian to an Epistolary is probably worthwhile either.

If I was to drop the Epistolary upgrade and the Thunderfire Cannon, I'd get 175 points to spend. That could net me some Devastators or an 8 man Assault Squad with Power Fist and Melta Bombs. What do you think?

The bikes are a "Suiside unit" In that they do one job well but are fragile. Becuase there are only 3 they cna easy to kill/rout However i feel Turbo bossting turn 1 and then using them might work. My 75pts Sentinel took out 4 Ravenwing Bikers the other week and he had poored alot of pts into that unit.

Depends on what you want form your army. A Thunderfire cannon is an anti-horde weapon and not used much becuase of how fragile it is (being artilary) and it's lack of power in stoping anythign other than Orks or Tyranids. Hower i like it but i am an Imperial Fist player so fluff means i biest towards it.
The Assault Squad sounds the better choice of the 2 however i see little point of having meltabombs on a powerfisat/thunderhammer armed modal. If you want to use up those last few pts then upgrade it to a Thunder Hammer. A little added ability never hurt cna can stop your men getting shot should they fail to completly destroy that Landraider etc.

Well the idea with the bikes was just to provide a unit which might be able to Turboboost and take out a tank, though I'm worried that only 3 models means they might die before they can do anything. I do like the feel of bikes in a Marines Errant list though... Would it be worth adding any extra riders you reckon? (even if bikes are expensive in terms of $)

As for the Assault Squad, I was thinking that the Melta Bombs would allow them to chime in on the AT if needed, as I'm worried about the strength of that component. If the bikes go quickly, the Dreadnaught gets stuck in, I'm left with the Deathwatch for any AT capability - and that's a single combi-melta. Though the Termies could prob do something.

well 9 out of 10 times the powerfist is more useful and only really any use agianst Landraiders whihc they can struggle to damage otherwise.. Personly i love bikes, it's jsut that mine are Blood angel ones so they don't see as much use (Bikes in an Imperial Fist army seems wrong) Just make sure you convert them to have meltaguns as the bikes kit is awful and too expensive.