My son's took two years because children were involved, but it can be a year if there are no dependent children. Mind you this is Scotland, it may be different in England, Wales, etc.
You can do it yourself cheaply, quickly and easily by going to your local county courts and asking for the application forms. They supply all the step-by-step information as you go along. This doesn't sort out property or access/custody of children however and you'd be better having a solicitor in those circumstances.