Thanks for the help so much.
So the question I am unsure of is what makes a good transient response compared to another, I sort of felt like the speed (tightness of the curve) to return to the steady state is desirable to be as rapid as possible; within the context of acceptable ripple and the lack of ringing / misshape of the profile curve or the output voltage. Is this correct and should I also look for ringing in other areas of the circuits?
This is the PS circuit I am trying to model, with approximately the design I am moving towards btw. The 6c45 takes voltage from halfway up the doubler of 2 x 5u4GB rectifiers, and I have struggled a bit to have confidence this is modelled correctly.

