Issy, you have my sympathies. My sister also hates to cook, but also has the complications of being a caregiver for hubby and our brother. Reduced her angst a lot when I spent a week with her working out about 30 menu ideas. Chopping veggies can be done the day before or day of. Reduced a lot of her stress not having to think about what to make for dinner and getting it done in 45 minutes or less. Yes, she gets rotisserie chicken - because I'm bringing it.
We visitors always bring a meal so she has just one less thing to concern herself about and can just visit.