Aww, bless you for thinking of fostering due to your circumstances, do get in touch with local rescues, as not all rely on foster homes. Having only indoor access isn't an issue, it is nicer for them to be indoors than an outdoor pen, and most fosters have to be kept indoors till a home is found. Working isn't an issue either, I work full time, and know quite a few rescue people who work either full or part time, as long as you can find the time for them, it isn't an issue (I rarely do things in the evening to give them time). The main thing is being able to give them the love and attention they deserve, while being able to let them go when a home is found.