co-sleeping - which blankets? Stupid question but can't decide!

[MrsKitty]

DC2 is on the way, due October, and we have bought a bedside cot with the intention of semi co-sleeping IYSWIM.

Am paranoid about the whole duvet issue so plan to ditch it entirely till baby is bigger. It's going to be cold though for a good few months from October though I imagine so I am looking at alternative bedding. I know sheet/blanket is the recommended alternative, but what type of blanket?

Acrylic cellular blanket (cheapest option)
Wool cellular blanket
cotton blanket
Merino Wool Blanket

I know I'm being a bit PFB about this, but hey - I'm looking to get as much sleep as possible for all of us this time around

I have co-slept with both my dc's.

We just pushed the duvet down in a u shape between us, and then the babies slept in a grobag, with or without extra blankets depending on the weather.

Invariably they also ended up under the duvet too, they are both fine.

I you are concerned then any cellular blanket is fine, though acrylic ones are going to be more sweaty.