This operator can help select your international flights, but you'll have to book them yourself help
Fly to/from Kilimanjaro Airport (JRO - Check price) near Arusha. Or fly to/from Arusha Airport (ARK - Check price) via Dar es Salaam or Nairobi (Kenya)
A transfer from and back to the airport can be arranged for an extra cost
Additional accommodation before and at the end of the tour can be arranged for an extra cost
I did the Arusha National Park tour with walking safari, and it was a fantastic tour (my daughter loved it as well). We saw so many animals driving through the park, and our guide was especially good at spotting different kinds of monkeys...