The breaks are staggered. It's not every child in the school for the playtimes. All of the areas they are allowed in are monitored, the younger children are not given quite a free reign as you have listed. Not the very small. There is constant movement in the school, adults everywhere, and the staff room is based in between the playing field and canteen. There are no hidden corners and even if they were there is a huge sense of fair play in the school and bullying is not tolerated. The children would not be scared to say if they saw something. But it's not something I worry about, the school has a big "being a friend" teaching policy and the school council take their looking out for each other stance very seriously.
My 6 year old went off grid with a friend, they went to see the counsellor because she's nice. I went in and had a chat with the primary head to discuss how it was dealt with and their absence was noticed within a couple of minutes and there were 8 staff immediately mobilised to find them. There is a system. As far as getting out of the actual school, no chance. The chaps on the front gates see me at least twice a day and I still get checked every single time.
I don't know if you looked at all of the pods but they are all the same layout for primary, classes around a central area. I like it, it has a community feel.