Hydrangea won't die, but any weeds use up moisture that might be needed by your desired plant. If you don't mulch, some kind of weed will try to grow, and there are worse weeds than Creeping Charlie.

Creeping Charlie, "Glechoma hederacea" was once sold as a ground cover so it may not be as bad as many think. If you don't mind a polyculture lawn instead of a monoculture lawn, this is one of many "weeds" you can ignore. You should be able to fairly easily keep it under control in any planitng bed as long as you pull the plants out before they get too large since they can develop a very large root.

I've seen many Hydrangeas with various ground covers. I think it's pretty and wouldn't bother it unless in beds, just like you're doing. Many lawns around this area turn purple in the spring, Glechoma, Lamium, Verbena. Hardly any monoculture lawns - they're so much prettier than just plain grass. Any low, soft creepers are welcome where we mow. We don't use 'cides either, made by those who have decided so many pretty flowers are weeds and that we are failures for not using their products to eradicate them. I don't buy it, figuratively or literally. If something grows that I don't want, I dig, pull, or smother it.