Yes, you can use milk, half and half, or skim milk in coffee. The consideration is to have the fat from them any of these counted into your TOTAL recommended fat for your level.
So, if you're at 1,600 and 17 grams of fat per meal be sure to include the fat in the half & half, for instance. If it takes you over your recommended fat then use LF or skim milk to be sure you're under.
Think of alli as a game: You're really trading off different foods so you stay at, or close to, the recommended amount of fat for your level.
I hope this helps. Please let me know if you need anything else.
Pat Baird, MA, RD, registered dietitian