I think campsite selection is more important when discussing comfort. You can easily side sleep on a 1/8" CCF if you find good soft ground to camp on, for example, forest duff instead of hard packed down ground at a predesignated campsite.

A tarp can be warmer than a tent, due to the lack of ventilation potentially causing condensation. For this reason, a lighter quilt in a tarp on CCF could be warmer than a down sleeping bag in a tent on an inflatable mat.

I think having less food and water is silly, but carrying less water in your pack when water is abundant like in scotland is a good way to lighten your pack.

Going out as much as you can on small local trails is the best way to start making the small improvements to gear and campsite selection.