This operator can help select your international flights, but you'll have to book them yourself help
Fly to/from Abeid Amani Karume Airport (ZNZ - Check price) on Zanzibar. Or fly to/from Dar es Salaam (DAR - Check price) . There are daily ferries between Dar es Salaam and Zanzibar.
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 went with Smiling Tours to Mikumi and Nyerere National Park and I can recommend the company in terms of organization and reliability. The staff is very experienced and Moshi was available any time to answer our questions during the trip....