If that is your first cheese you are off to a MUCH better start than I ever dreamed of! Great job.
I don't know if you use a Ph meter or not, but I would recommend getting one.
You stated that the cheese was a little bit chalky and this could be due to too low of a final Ph in your cheese.
Cheddar, (in any variety) is a VERY tough cheese and from appearance, you've done a great job. I'm certain that with a Ph meter you could take this cheese to the next level and turn out something that is truly commercial quality.
I'm not dissing your effort in any way shape or form. For a first cheese, this is absolutely fantastic! I wish I would have given such attention to detail, to create this kind of example, when first starting out.
I'm simply trying to give someone a bit of advice, that shows such great promise.