Glad to be of assistance.
The Code of Practice specifically refers to what's on their website - so, if you comply with that, I can't see how you can be faulted.
2.1 Admission authorities must set a timetable for organising and hearing appeals that:
a) includes a deadline for lodging appeals which allows appellants at least 20
school days from the date of notification that their application was unsuccessful
to prepare and lodge their written appeal;
2.2 Admission authorities must publish their appeals timetable on their website by 28
February each year.