Summary
School admissions and catchments matter because living near a school does not automatically mean a child will get a place there. The real test is the published admission policy for the entry year, including oversubscription criteria, distance method, sibling priority, faith or aptitude rules, and any fixed catchment or priority area.
Definition
School admissions are the rules and processes used to allocate school places when parents apply. A catchment area is a defined priority area used by some schools or local authorities, but not all schools use one and being inside a catchment is not always a guarantee. For a home buyer, the practical check is whether the exact address is likely to qualify under the current admission arrangements and how distance is measured.