I was at Wood Green library (children's bit) 2 weeks ago and it was heaving with children (who were just running in circles) and some bored uninterested looking mums sitting round on the chairs chatting with their shopping bags and ignoring the kids...
...or so I thought until they got up and said 'time to go back for lunch' and 1 of them had a Noah's Ark Nursery t-shirt on.
It could just have been a bad moment, perhaps they were very engaged and hands-on with the children (perhaps reading books or engaging with/extending their role play in the house?) but thats not the impression I got. I guess at least they had taken them out for a 'trip'.
It also seemed odd that just after they left the library had a short story session, which it would have made sense for the children to stay and enjoy?!
My only other experience with Noah's Ark was a mum, whose child has been there for a few months, came to see me because she wasn't that happy with her child being there (I'm a Childminder), but sadly I was too far away for her to commute. She said her little boy loved being outside and she didn't feel he was outside enough and that he didn't seem very stimulated.
Sorry, that probably isn't very reassuring to you... but if your gut instinct is worrying you then maybe look at some other places? Bowes Park is meant to be a bit better? Or Woodside is worth putting your name on their waiting list as fab when the children do get in.