That is not 100% right! When someone is born in France he DOES have automatically the french citizenship... only if your parents don't want you to have it... so maybe she could have the french passport...
No. She only has british nationality. You do understand what nationality means right? I'm not trying to sound condescending, but being born in a country doesn't automatically mean you get a passport there. She has a british passport, she's a british national.