flying at night is after all a VFR flight and you shouldn't be fixated on your instruments in the cruise - unless of course you loose any kind of ground/horizon references
which is exactly what does happen.
UK night training isn't done in anything like a dark night; they wouldn't be able to because the students need a visible horizon, and on a dark night there isn't anything at all to see out of the window.
The other thing is that, even on a night where one can see a bit, one can fly into haze/fog/IMC.
IMHO this privilege is not what it seems. One needs the IMCR or the IR to use it fully. And I think most PPLs know this, too, judging from the insignificant night VFR (actually, night=IFR in the UK but let's not go there right now) traffic.