Blimey, that's an amazing idea! I always write about wizarding world, not about harry but about world that he's into. It's seems like I'm trapped there, but I like it. Right now, I'm actually making a Hogwarts map with changes from Deathly Hallows, new towers, viaduct, marble staircase etc. During all these years all that learning about wizarding world expanded to a massive universe in my head, wizarding world in Britain I got over 6 years ago, I spent time writing all that and now I know every wizarding school in Europe and USA, every qudditch team, location of ministry of magic, absolutely everything, every detail. It's sick how big wizarding world became in my head. Of course, I invented, wrote all these informations cause I always wanted to know more, not more about Harry, more about Wizarding World, and JKR just didn't give away much, but she says:...I am aware of what I have created, the gates I have opened, but I'm not closing them, ever. I need a Potter break, but you feel free to explore it, only you know the limits.
I don't look at that like a hobby, like I'm a fan, I respect it, think about it and write about it like it's real and then imagination do the rest. Creates the world.
I'm actually waiting to repair my laptop and I want to finish An Appraisal of Magical Education in Europe book. It's my favorite book mentioned in potter series, it's because gives you reminder that wizarding world isn't just in UK, it's everywhere. Maybe near you lives some squib? Or muggle-born wizard, or there's a pub like leaky cauldron or quidditch museum or aurors office or wand store or house of rich family of wizards.
At the end, I haaaaaaate when I want to say a simple thing and end up with writing a novel >.< xD But I like your idea