Yes the marines are all male, sorry but thats their FLUFF, yes its sexism, but thats because the emperor was sexist.
Besides GW shouldnt supply female models for the sake of it, especially since theres little evidence for races like tau having many distinctions, and the ranges where they mainly exist in the fluff already have them, See DE and Eldar.
Sure Guard can have female recruits, but its mainly the males due to fluff reasons, they are fighting for mankinds survival and the officers are probably sexist
But GL with the letter anyway,
And to be constructive.
Male
Play Tau, and BT and HE. I played tau because a friend did, and I like the idea of using technology to counter your own weaknesses, BT are heroic and Highelves are magic pwners.
all other armies I just dnt enjoy that much, orks are idiots generally while some intellegence exists I prefer suicidal charges for heroism not strength.
Tyranids dnt have tanks,
and smurfs are cowards 'failed to defend the emperor'
BA and SW are inferior.
Necrons are Bland.
DE and Eldar I like, but not as bad *** as templars.