Originally Posted by
BackPacker
I would not consider setting 1013 optional, even if VFR. ATC will issue clearances and such, and will expect your altitude reports to be a FL instead of an altitude, once you are above the TA. Plus there's the quandrantical rule (UK) or semicircular rule (elsewhere) that requires you to fly VFR at specific FLs above 3000' AGL.
The UK is slightly odd in that, for VFR, the quadrantal rule is recommended not mandatory in Class G (which is effectively the airspace we are talking about as most Class D is part of one of the designated CTZ/CTA/TMAs with higher TAs). When receiving a VFR ATC service, I always seem to need to switch to whatever they want (QNH, QFE, RPS) for them to not dump me - which makes sense.