Just to let you know, I was advised to send an email to the Data Working Group so they can perform a redaction (all copyrighted information will be permanently deleted from the database). For this reason I would recommend that you do not modify anything in this area until this is done, to make this as easy as possible for them. You are of course welcome to edit things elsewhere in Stevenage in the meantime :)

Now some small pointers - for an apartment building, use building=apartments, not landuse=residential + residential=apartments. You can see on the map that they are a different colour to the rest of the buildings you added.
- Use 'Q' to square buildings
- highway=unclassified is for rural roads, in a residential area use highway=residential for normal roads and highway=service for thinner access roads serving a couple of houses.
- https://www.openstreetmap.org/way/1442117777 has been traced slightly incorrectly, it should be a perfect rectangle, but you have followed the roof line which has been projected by the imagery, which is at an angle. In reality this roof doesn't extend out in a triangular shape. If you are editing tall-ish buildings you will notice how the imagery can distort their shape slightly, it's a good skill to be able to counteract that!

I hope that's all ok for now, let me know if you have any problems editing in the future, I would be happy to advise/review. As you can see, there's a lot of blank areas in the rest of Stevenage that also need attention!