Child's filled duvet/quilt - any help?

[GingerRodgers]

My daughter has a mamas and papas cot bed quilt which essentially feels and looks like a duvet that's attached to the cover? Iyswim.
I'd like to make one for her new bed but wondered if it's as simple as sewing the filling into the material?
The m&p website says it's polyester filled and I've always just chucked the whole thing into the washer. Quite like the idea of that rather than separate duvet and cover.
Am I mad? Is there a good reason to have separate?
Any ideas if it's simple to make?
Any help really appreciated.
Thanks

Anyone? (Bumping)

I used something like this to make a quilted blanket for DHs nan

www.fabricland.co.uk/quilting.htm

Sorry, I don't know if this is a suitable option for a kiddies quilt

Thank you just, I'll have a look at that.

You could use the stuff linked to or two layers of fabric and polyester wadding in between. Its sold in fabric shops and there are usually different weights.

You could just add a top and bottom to it a bind?