You can use various pour-ons, all of them come in quite large bottles (but with a couple of years of use-by dates usually), for example Eprinex and Spot-on. For Spot-on I use the sheep dose, and it has worked well, except for the long-coated GG's this winter. If you have a warm day you can also give them a wash/shower with an appropriate shampoo and immediately dry them off, put a rug on and keep inside until they are dry.
For milking goats I normally keep a 7 day-withdrawal period for humans drinking the milk.