The amount of time that you will work away from your family will depend on the kind of job you get. It is common that work hours are defined by the industry. For example, if you work in an office in a high tech company your hours will likely be Monday through Friday with 8 hours a day. It depends on the company and the kind of job that it is. In retail, like a department store, you will like have to work long hours, with various days off that are not set, and work holidays and weekends. Firemen usually have a split week where they are at the fire-house a certain number of days then off the other days. For example they may work one week Sunday - Tuesday round the clock because they have to be available for emergencies, then off Wednesday - Saturday.
If you are concerned about the time commitment, I would do a job search and you will see different requirements such as travel requirements 25% would mean that out of every 4 weeks you would be traveling 1 week.
I hope this helps.