Hi Mary
You will need a soft-sided holdall for the safari and another case for the second part of your holiday. You can check these in separately as long as the combined weight is no more than 20kg.
You don't have to pack your soft holdall inside your main case if you don't like that idea.
You are also allowed to take hand luggage (eg a handbag or small rucksack) in addition to your main case and soft-sided holdall - again, that's entirely up to you.
I hopes this clarifies things for you.
Kind regards
Olly, your editor