One more completely different piece of advice: finally stop talking about "spots" when you actually mean (recessed) spotlights, which can definitely produce a broad light. Whether you design them as LED panels or rather as smaller round spotlights is a matter of taste.
On the subject of dimmers: I would always do it, and if necessary, ask a more capable electrician who does not spread such nonsense. Of course, if it’s supposed to be done properly, it usually costs more than the standard 08/15 super cheap China sockets with GU10 bulbs, but it’s worth it. Basically, I think you can get by with the number of spotlights drawn in (plus wall lamps, floor lamps, other ambient lighting) if the spotlights are chosen correctly. For example, we have on about 50 m² (living/dining) "only" eight dimmable recessed spotlights (four living, four dining), which have enough power and a wide beam angle. With this, you can make it cozy, normal, or really bright—depending on the need.
The advice to draw in all the furniture and then plan can only be emphasized either way.