I am taking my 3 primary kids out a week before the end of term.
I wrote a letter, giving the dates and reason (family obligation in the USA). I received the confirmation back from the headteacher, which happened to be on a tear off slip of a form letter - therefore, the school actually has form letters for this kind of thing.
I did not grovel in my letter - just wrote it in such a way that I would be taking them out.