As a DA
player i would swap 1-2 groups of marines to Scouts(5x) squads because it is good for screening and snipe some low wounds hqs
. The RW
bikes isn't that useful so i would swap them for RW
black knights instead.
Don't know with units you got at home but azreal is really good in my opinion so choose him instead of Talonmaster or lieutentant.
Land speeder is okey but you can get a pred or razorback for more dakka and toughness on the board.
I am a new DA
player so still learning also this is some advice i can bring you
Good Luck man!