There are very many frankincense based perfumes; I haven't smelled the Lush product you mention, but knowing Lush's soaps, I doubt it'll be close to true frankincense fragrances, which are sort of lemony and have a very churchy vibe. Perhaps patchouli could be safer. Before committing to a purchase, it would be good if she could smell it beforehand, or at least she could return it to the store (perhaps you can ask for a vial to go with the purchase?)
Chanel No 22 is close to Chanel no 5, but has incense and some swetness, so it could suit her. It is however somewhat expensive.