I have no experience with artificial light but I keep my succulents indoors right by a window facing SW (within the 1 foot distance you mentioned) and they do fine with natural light over the winter. As a general rule, if your succulents can "see" the sun for hours a day most days, they will be fine. If not, maybe start plugging things in.
Also be sure to back off on the watering (assuming this is your first winter with succulents), especially if it's cold or dark inside. You probably will want to water less often (half as often or less) during late fall and winter, because the soil will dry out much slower under those conditions. On the other hand, given permissive conditions (strong light and room temperature days with cool but not cold nights), your plants may continue drinking and growing close to normal.
