Wedding insurance claim - help

Hello there
Has anyone claimed with John Lewis Wedding Insurance? My mother got diagnosed with cancer at Christmas and may not be feeling well enough to come to our wedding abroad in September, especially with the risk of going to events and catching COVID, but I was wondering what was required to make a claim? Did you have to provide medical records and if so, which ones? It’s quite close to the wedding so want to make sure we have our ducks in a row before hitting cancel/postpone.
Any advice would be appreciated! Thank you 🙏🏽