Welcome to Librarium Online!
This is my first time tring to build an army I would love some input.
Company Command Squad - Commander with boltgun, 2 snipers, 1 granade luncher (67p)
Platoon command Squad - Commander with bolt pistol, 1 gurdsman with meltagun (42p)
infantry Squad - 2 flamers (62p)
infantry squad - 2 grande lunchers(62p)
Heavy weapons - missile luncher, Autocannon and mortar(75p)
Veteran Squad - sargent with powerfist and boltpistol, 1 flamer (92p)
Ratling Squad - 3 ratlings (30p)
2 scout sentinels (70p)
The idea is to have the heavy weapons with the company command and ratlings in the rear and using the sentinals in front of the force to preocuupy units do it will take them longer to reach my lines or to use them to take out enemy heavy wapons in the rear (to race them forward behind his line).
I am not sure if I should have the sentinels as diffrent squads to get more flexability or to use them together...
3 ratlings aren't worth it, and all those boltpistols are meh.
drop them and get another sentinel!
same is true for the snipers in the CCS, and the powerfist of the veteran squad sarge.
oh and NEVER mix heavy weapons in the same squad. go for 3 autocannons.
The main thing with this list is what each unit is supposed to be doing.
Firstly as said above don't mix heavy weapons in a squad take three of one type. Autocans are a good choice as noted above. The company command again mixed weapons drop the bolter and grenade launcher.
The standard squads are illegal it's one special weapon only so drop one of each.
Vets are taken for their higher bs so never give them flamers and also they can take more than one special weapon. With regigging you have two grenade launchers place these in to the vets then swap out their flamer for the pcs's melta. Should be getting to a more usable list by that point other stuff is personal preference IMO.
Hope that helps
Just to add to what has already been said. You should try and maximise your command squads where possible, ie take 4 special weapons. Your CCS would do well w/ 4 Grenade Launchers. You Heavy Weapons would also be better off inside your current IS. A common and effective loadout for IS is Autocannon and Grenade Launcher for 65 points. If points are really tight you could even do without the GL's. Sentinels are better off w/ Autocannons, but at 500 points Multi-lasers are quite effective. Ratlings are also ineffective. With these changes you would not only make your list more effective, but save points in the process for additional units, perhaps a third Scout Sentinel.