I've just googled in and eventually found that the rear lie-back seat is suitable from birth. There's a ponce-tastic description of it on a site called babyzoop or something which is of no help but the mothercare site says it's ok.
The baby zoop website just tells you how fab you'll look in starbucks and that everyone else will be jealous and then you can tell them how to pronounce Jane properly cause it's Spanish don't you know. No useful info however
I always used the car seat for my littley, but I think with a footmuff of sheepskin thingy to cosy it up it would be fine. I wouldn't use it for a newborn without extra padding, personally, as there are no sides to the seat.