I want to give a complete picture of the costs and logistics of a 3-week trip to Eastern Africa including a safari, because the price range is enormous.

Flights: round trip from London to Nairobi runs $600-900 on Ethiopian Airlines, Kenya Airways, or Qatar Airways. Turkish Airlines is often cheapest via Istanbul. Booking 3-4 months out and using Google Flights price alerts.

Nairobi (3 nights): reasonable budget accommodation in the tourist-adjacent Westlands area runs $15-25/night. The Nairobi National Park day trip ($35 entry) is worth it — the only national park in the world inside a major city, with wildlife visible against a city skyline backdrop.

Amboseli National Park (3 nights): campsites outside the park boundary cost $15-25/night. The park entry is $50/day per person. A shared jeep safari (organized through a local operator in Nairobi, not through an international tour company) costs $80-120/day for the jeep split among 4 people.

Zanzibar (5 nights): Stone Town budget accommodation $20-30/night. The island beaches range from $15/night basic guesthouse in less touristy Matemwe to $80+ in Nungwi. Stone Town for 2 nights, quiet beach area for 3 nights.

Kilimanjaro attempt (8 days): the Marangu route (cheapest, most crowded) costs $1,800-2,200 for a 6-day attempt through a licensed operator (legally required). This is the big cost anchor of an East Africa trip.

Total without Kilimanjaro: approximately $1,600-2,000 for 13 days including flights. With Kilimanjaro: $3,400-4,200.