They don't block the entire foot, just the area that is painful so she should remain rideable.
Yes, she does have a healing up period, about 6 weeks, I think.
Interesting that the blocking is partial. I didn't know that. In discussion I've ever had about riding horses after nerving, it has been my [false] assumption that the heel and the whole foot was numb.
My vet's wife had a horse she rode in dressage for years after nerving for navicular. The precision of movement and soundness demonstrated in dressage tells me that it is quite possible for them to 'find their feet' and still have good sound movement. All the best to you and Winnie and your daughter.