🚀 go-pugleaf

-> Each evening at about this time of year one sees a very bright planet
-> lying to the southwest from my position at around 52N. It is at, I
-> would judge  45 to 50 degreed up from the horizontal. It is very
-> bright.
-> Is it Mercury ? Is it Jupiter ? I don't suppose it's Venus - that's
-> called "The Morning Star", is that right.

The planet you are seeing IS Venus.  It can be a morning or evening
"star" depending on its position.  However, it will NOT always be
visible in the evening "this time of year," since it takes 584 days to
return to a comparable position.

-> Whichever planet it is - how far from Earth at this time of
-> respective orbits and what is the maximum and minimum respective
-> distances from it to us at different times.

It is currently 0.751 astronomical units from us, with a minimum
distance of .277 a.u. and a maximum of 1.723 a.u.

-> Last, whichever it is, what distance please from the sun at aphelion,
-> at perihelion.

I don't have the exact distances easily available.  Venus has a very
nearly circular orbit, with a mean distance from the Sun of 0.723 a.u.