There's a lot of bad advice up already. Most species of tortoises should not eat fruit or veg. The majority of tortoises available in the UK need a 100% weed diet, no fruit and no veg. Such species include Horsfields, Hermanns and Iberas. Some tropical species are available but are more challenging to care for as they often grow very large and require different environmental conditions that can be challenging to achieve.
I don't wish to judge your daughter but generally kids tend to get bored of their pets after a while. But when i was 11 i got my first bunny and i loved her to bits for 5 years until she sadly passed away. I was hooked straight away and now have six beautiful bunnies the oldest been 8 years old. I really think you should check out these links on tortoise care and decide for yourself if you can make the commitment say if she did get bored of the tortoise.
There's already a lot of bad advice on here. So please check out all these links. The first is the tortoise trust website, it has plenty of in depth caresheets on the care of numerous species of tortoise. I would recommend you look into Horsfields and Hermanns as they are easier to maintain in terms of an enclosure and diet. Both these species require a 100% weed diet so you can pretty much feed your tortoise for free.
http://www.tortoisetrust.org/backidx.html
Please read up on herpes in pet trade tortoises too. I recommend you find a breeder and not a dealer or a petshop to purchase your tortoise from. Petshops often give out bad advice and convince you to buy unnecessary expensive equipment such as vivariums and heatmats and recommend you feed your tortoise pellets. A good breeder will recommend a tortoise table set up and a highly suitable diet for the species concerned.
The next link is an excellent tortoise forum. I suggest you check out the housing section. There are plenty of pictures of both indoor and outdoor set ups. Any tortoise you plan to get will require both. Your tortoise will be perfectly fine spending much of the summer in your garden in a safe suitable enclosure. You may require an indoor set up for unsuitable weather, and of course in winter you will be most likely hibernating your tortoise which also saves on running costs.
Also check out the edible weeds section as weeds are a far more superior diet than supermarket salads and veg. Plus weeds are generally free so won't cost you penny to feed your tortoise. If your a little affraid of picking weeds then you can always purchase weed seeds off the internet. I buy some off ebay just type in tortoise seeds.
http://www.shelledwarriors.co.uk/forum/
I know i'm going on but i do love my tortoises as much as my bunnies. And i think its best you do as much research as possible before you and your daughter make a final decision on whether to get a tortoise. If you wish to buy a hibernating species from a breeder you may have some difficulty as many breeders will be winding down their hatchlings for their first hibernation.
Hope this helps.