Please do not clutter the board with
duplicate posts. Be patient and you'll get responses if people have suggestions / feedback to offer (responding to queries is voluntary). Reading
this will be useful.
Coming back to your question - Honestly, the choice is yours and depends on your circumstances.
Whether you want to come to UK on your first, make efforts to become economically active and once you've settled down (a job + place to live) the get your family to join you. Or you want them to come along with you in the very beginning itself.
If your kids go to school, their education is also a priority. Maybe you would want them to contniue their studies in Afganistan until such time that you know for sure that you have relocated to UK for good (or long-term) and can maintain a family here. You might also want to get your children to UK closer to the start of academic session in schools, so they don't lose out on a year!
In a nutshell, it is up to you!
regards