3 season sleeping bag/quilt?

[AyrshireAlps]

That's a good shout actually, I like the sound of that.

[Scottk]

Buy a sleeping bag now and if you find it too cold buy a quilt and use both in winter. You can boost your warmth with a down jacket if you get cold. The sleeping mat makes a big difference too.
I would suggest a full length zip-my bag has a half zip and gets too warm.
Having a decent meal and hot drink makes a big difference to how warm you feel.

[BigTed]

For small pack size and weight warmth ratio it has to be down Everyone is different but I think a fill weight of 300 to 350g is about right for a 3 season bag. April to Sept is easily including camping nights a few degrees below freezing. In that case I might boost my bag by wearing my lightweight down jacket inside it.
Having a bag that is a fairly loose fit helps in this regard. In Scottish conditions being too warm with a 300g fill bag is unlikely to be an issue. Drop bag to your chest and unzip it a bit.

Anyone who is over 6ft in heigt or 15 stones in weight may find standard bags are too small. PHD designs do nice bags in numerous lengths and widths. (at a price)