Surely if they're not on the chart, no zone, no different treatment to random vfr traffic
The presence or not of an ATZ is irrelevant, but...
1/2 dozen strips/airfields crowded in there, all of which are by Air Law entitled to folk flying nearby to mind their pattern
...they might not even qualify under the definition of an aerodrome, and certainly if they are not shown on aeronautical charts, a pilot could hardly be expected to "reasonably know" about the strip in order to comply with Rule 12 (UK).
2 s