With my children during the V&A visit, I am focusing mainly on three areas:
1) Resilience: Frida being physically in pain (after polio and a bus crash) found the strength to create a beautiful art to express her emotions. Look together through Frida's self-portrtaits and see what she was drawing and talk to the children why.
2) Frida's relation with Mexican culture thought her clothes and jewellery (e.g. jade stones used in Mayan rituals) - girls especially can choose their favourite dresses on the display to draw some of them in the notebook.
3) Frida's controversy: how she portraits female's beauty, her political and religious views (depending on your children age).
Some logistical tips: The tickets are sold out for the next three weeks but 100 of them are released every morning at 10:00 at the museum. If it does not work, you can plan you visit later as the exhibition is till November 4. There is also a different solution, if you become a V&A member (£70), you do not need a ticket for the exhibition, children can come with you for free and you get 10% discount on any purchase at the museum.
Fridays, V&A is open till 10 pm and the restaurant has live piano in the evening and garden space has a puddling fountain (that kids are happy to splash in). It can be a nice summer outing for grown ups as well as the kids.