Also worth mentioning is that we don’t have duvet covers, stopped using them a number of years ago.
We have a flat sheet on top of us, with the duvet on top of that.
All our duvets are Fogarty ones which are bright white and very soft. They get chucked in the washing machine when we change to a different tog one.
When you say lightweight do you mean Tog weight or how heavy it feels. I have a double tog synthetic 9 and 4 tog but the duvet itself is lighter than the feather mix my daughter has but the togs and warmth are the same. From John Lewis. The single one is perfect on a 4 ft bed with no hangover