you raise that sort of stuff with your MP, the teachers' and parents' representatives on the board of governors, the parents' surveys that the school and ofsted conducts.
you alone writing a letter may not impact on any of these people. a large number of parents doing so might.
is that going to make a blind bit of difference to your child's day to day education? no.
the more these things are brought to the forefront by parents through the established channels then possibly the more seriously it will be taken up someday. I am not holding my breath though.
Hopefully, your dd will hear grammatical English being spoken and read in other parts of her day which will counteract the shortcomings of teachers.
I grew up using English in school only and in books i read. Not at home or in play with my friends. I know the teachers taught me back then were not completely native speakers either so made mistakes. It was my desire to learn English that made me as competent in it as I am. These days, with kids more attracted to the bright lights and bling, bling of telly, playstation, mobiles and ipods, learning and using proper English is way down the list of their priorities. And i have to compete with that when i am trying to teach enough grammar to raise their achievement in MFL!
personally, the only way kids will learn grammatical English is to bring back grammar in schools and a very early age. It is a chicken and egg scenario though. How do we get our hands on enough people, money and time to train all the current teachers in correct usage of the English language? Surely the gov't has better things to spend its money on rather than the education of the next generation.