I am leaving Dubai in the summer to take my kids back to University and boarding school. If I stay out of Dubai for more than 6 months will my residency visa be automatically cancelled?

If you stay out of Dubai for more than 6 months and you have not cancelled your visa, it is usually cancelled automatically and you may get a fine as well as you re-enter Dubai. If you were employed, you might also be registered as an absconder, so you may also get a ban. The best place to check is with the Ministry of Labour and the Department of Immigration before you leave.  Read more here