In order to have a home office, you need a home-based office space. Some people have that inside their home. Some do not. The point is that it easy and relatively inexpensive to add if you need a degree of separation between work and home.
One example is StudioShed. Third Wave has blogged about it before. But, here is an example by Gail Seigel. She is not a lawyer, but a full-time jeweler. It does not matter as it shows the versitality and possibility of the space. After weighing her options, including renting a space and buying a larger home, she decided to install a 14'x10'x9' prefabricated a solar-powered backyard shed by Studio Shed. It includes electrical and plumbing, and has FSC-certified TruWood Collins siding, corrugated metal, a foam-insulated cement floor, energy-efficient windows, and eight 235-watt solar panels. Not counting solar panels or other options, Studio Shed offers a shed of this size for about $7,200 and generates enough energy for the shed and part of the house.