Englishal: I think your suggestion about different inbound & outbound heights from an airfield is a good one. Funnily enough, the local training organisations at Bournemouth do in fact have their own "voluntary" system of 1700' outbound & 1300' inbound (I think...) - someone can confirm.
Saw the same when I was flying from St Cyr under the Paris TMA (terrain 300-500 AMSL below) & TMA @ 1500'QNH above, where we operated 1300' & 1100' QNH respectively along strict in/out routes. There you really needed to separate vertically as they passed within less than a km of each other!
One other major thing we could do: GET RID OF OUR INSANE O.H.J.!!
Nothing is better designed to put lots of unfamiliar aircraft in:
(i) a jumbled mess in the same piece of sky,
(ii) not knowing from which direction they're coming,
(iii) followed by a disorientation by putting them in an artificial turn that bears little relationship to the underlying circuit,
(iv) dumps them out potentially somewhere in the middle of downwind meaning the appropriate checks get rushed.
Unless there's something I'm missing, either the French-style "rectangular" OHJ or US-style "45 degree join" must be immeasurably simpler & safer for all concerned.
BFA