First off, relax. It's just beer. You have made beer before. AG is just making beer at a higher level.
Don't worry too much about water chemistry. I have brewed nearly 100 batches and have never worried too much about water chemistry. Does it make a difference? Well, yes, and a sizable one, however, you have made beer before and all you are adding to this brew day is the sugar extracting process. It may be a very scientific process, but it's not rocket science. House wives, monks, and hillbillies like me have been doing this since the beginning of time. Some very good beer was made before anyone even knew what yeast was. While water chemistry makes a huge difference in the final product, most water can make good beer. Give it a go, and correct any issues you are intolerant of in the next brew.
Know that a Blue Moon clone does not have a lot of complexity to hide off flavors. Keep that in mind. Pay close attention to your chill and and even closer attention to your sanitation and fermentation temps.
Heat more water than you think you will need. It never fails when doughing in, you find yourself a few degrees low every time you don't have any more hot water to add. Like
ApolloSimcoe mentioned, have some cold brewing water handy also. Too high a mash temp is as bad or worse than too low.
Have a home brew and boil....Hard! Let it roll long and hard. You can always ad water if you lose too much. Leave the crap in the pot when you rack off your wort. Hop debris and hot break have no place in your fermentor, and with a beer as light as Blue Moon don't chance the off flavors or added haze they may bring along.
Above all, enjoy yourself, after all you are making beer. What is cooler than that?