I don’t make cream drinks often, but I have found whole milk, half-n-half, and heavy cream reasonably interchangeable in a pinch. The results aren’t identical, of course, but I’ve often been surprised how good a job whole milk does in place of heavy cream. Most of the time, it’s half-n-half that I have on hand (because of coffee) so that’s what gets used. No complaints. See also: Grasshopper - #8 by martin which I did test three ways.