GB wrote:

I have more or less decided that what we want are some LED panel
lights that can be screwed to the ceiling. I'll check the output but
4 600x300 panels should do it, or possibly 600x600s. Some of those
can be dimmed, apparently. But I can't seem to find any that also let
you change the colour temperature/colour.

Don't know about 600mm versions, but some panels have both warm and cool
LEDs and alternate between them each time you turn them on.

these aren't cheap, other may be

https://www.ledecolite.co.uk/rgb-cct-colour-changing-panels.html