A simple appeal letter against oversubscription can be found here:
with over subscription critaria being put down by school, it is making my case weaker
I'm not sure if I've understood you correctly, but you are not limited to the school's oversubscription criteria when you go to appeal. An appeal panel is free to consider any arguments you put forward.
we are moving from london to canterbury
It is better to appeal either after you've moved, or when you have evidence that you are fully committed to the move (e.g. a contract with a date of completion for house purchase). This is because being in catchment might strengthen your case.
i would prefer all girls school over mixed school
For an appeal you will need to give reasons and provide evidence if possible (for example, a Muslim family would be advised to get a letter of support from their Imam).
I'm afraid I can only help with appeals, not choice of school.