Here are some links to sully care.
Can I ask does she know how big these grow? they are huge when they are fully grown and will need a paddock, as they are grazes just like a horse.
You definately wont need a lawn mower with these beautiful yet costly tortoises
Tortoise Trust Web - Geochelone sulcata
African Spurred Tortoise - Geochelone sulcata - Darrell Senneke
The Sulcata and Leopard Tortoise