I suppose this would be a recent startup to fill the void left by Hogwarts' closure. A reasonable idea to be sure, but I have several concerns about.
First of all having the potions classroom outside is a disaster waiting to happen. There's a reason high schools don't put the chemistry lab next to the tennis court, because it would be all kinds of safety violations. Potions would need to be in an enclosed, well ventilated room, preferably on an upper story.
Having Charms and DADA outside also seems dubious, considering that this is in Britain, and the weather will be playing merry hell with your lessons.
The school is also understaffed. Four teachers covering three subjects each means they'll be incredibly overworked, even more so if any of the lessons will take place more than once a week. It also requires them to teach outside their knowledge base; one person doing History and Runes seems reasonable enough, but Transfiguration too? You don't see real-life history teachers doubling in physics. It would make more sense for every subject to have its own teacher, and the core subjects could do with multiple teachers.
As for students eating in their rooms; I hope you pay your janitorial staff well is all I'm saying.
The Houses. Why do you have them? What purpose do you serve? Considering how badly having houses went for Hogwarts, I would think whoever created the next school would decide not to bother with them. Especially since you only have two, that seems like recipe for pointless conflict, and teenagers are perfectly good at doing that on their own. And the ceremony is uncomfortably reminiscent of early modern witch trials, not to mention pointlessly cruel to the Greens. Also, having the two sides be the Greens and the Purples is hilarious to anyone who's seen Babylon 5.
And the classes, there's only one difference between your classlist and the Hogwarts curriculum. You could be creative, try to come up with some new ideas here. That's my problem with this whole thing, it seems like very little creativity was put into this, so it just seems like Hogwarts-lite. Like I said at the start, the idea of a new magic school in Britain is viable, but you need to put a lot more thought into how it will be run, and how to distinguish it from Hogwarts.
