I wondered if you were interested in say, WHS, and didn't get a place at that school if you qualify, then under the old system, you could have looked at alternatives further away, e.g. the Aylesbury schools.
Not really, because each school only had a very few places, so only children living fairly close by would gain places. The only way to "override" that was through an appeal.
However, from what you say, for late entrance, you really should only apply to your nearest / catchment GS?
Yes, the nearest school, and catchment if possible, simply because it makes for a stronger appeal case. The only exception would be if you have a potentially very strong case for a second school - perhaps though a sibling connection, in which case a second test might be worthwhile.