"Think I need to upgrade my eye* couldn't see any difference between HD and 4K in the telly shop."
Unless you have a really big TV (>> 60"), or sit really close, the difference between HD and 4K in terms of resolution is non-visible. Certainly, I can't see the difference between 4K and HD on my 49" TV (and yes, I have good eyesight) - this is borne out by the maths, too. HDR? I don't feel a need for increased contrast in the image I get, so, meh (I tend to find OLEDs look completely unnatural anyway).