I don't know anyone who doesn't want seconds or thirds when they try this. It's a gorgeous treat - the bacon is possibly a little OTT for something already so decadent but it really completes the dish. Enjoy!
For the mature Cheddar, find the strongest, stinkiest one possible. It gives this mac and cheese the punch it sometimes lacks. For a variation, you could also try adding a teaspoon of English mustard or some onion powder (fab stuff if you can find it) alongside the black pepper.