Flamers on the skyhammer are pretty useless except in a circumstance where you'd have locator beacons next to your enemy turn one. The only way to do this is with scout bikers, which aren't amazing in a drop list.
You're a LITTLE heavy on the melta
lol. I'd recommend switching the weapons on the skyhammer. Keep the assault marines stock, as I said, flamers aren't good, since you've gotta be within about 4-6" of a squad to make good use of them, and your assault squads should be going for a first-turn charge to tie up something.
Heavy bolters could be good, since you lack dakka, grav-cannons are expensive but pretty worth it, plasma cannons are kinda meh, when people spread their guys out(which they usually do, unless they're really new) you get off maybe 1-2 hits with a plasma cannon. Lascannons are pretty good but they're pricey for their 1 shot. Missiles are decent multi-purpose, I'd probably go with 1 grav-cannon squad if I were you. And a combi-grav on the sargeant.
Make your skyhammer Ultramarines
CT, so that they can get Devastator doctrines and just OBLITERATE something with
TL grav-death.
Instead of the tacticals in rhinos, take scouts in Land Speeder Storms. 2 of those are REALLY fast objective grabbers, and you can even deep strike them or outflank them if you want to do a null-deploy.(start with nothing on the board, dunno if you know that term since you're new.) give the sargeant a combi-melta and take a
MM on the
LSS, with
TL it's
BS 3 isn't that much of an issue. you can also keep it as a heavy bolter for long-range dakka. The heavy flamer is hilarious if you deepstrike it in with a locator beacon on one of your drop pods.
That's another thing I should mention. Locator beacons are AWESOME if you have
LSS or other units that can deep strike. I'd recommend it on the skyhammer, you can drop the scouts in turn 2-3 and provide some bodies and bolters to deal with stuff that would tie up your
devs. The assault marines are already doing this job, but they're probably gonna die pretty fast. Scouts with
CCW are nearly as good at holding the line as Assault marines are, but I'd recommend bolters for utility.
I'm not sure about taking the heavy flamer over Melta gun on the dread. 2 rerollable heavy flamers are pretty deadly, but he's str10 in melee and should be tasked with fighting your opponent's big bads, monstrous creatures, tough melee characters etc. The meltagun will be more effective vs those, and is
TL to boot... And you are pretty heavy on melta already.
Anyways, cool list, good luck and welcome to
40k