That sounds about right. KS2 Results and waiting for Feeder Schools was mentioned.
Will the Admissions officer keep getting ATF data up until Sept?
That depends on your LA - ours stops at the end of the summer term. However, by around now the data is likley to be changing very little: everyone should know who is going to which school, and you actualy need only a very small subset of data to put a student into SIMS - name, date of birth, that type of thing. Of course, if your school is like ours one of the main sources for updating information is the admission form, which our parents complete when they come to an admissions evening which is the same day as our New Intake Day. This might be another reason why your admissions officer is hanging on.