It's not been the end of my world. But I've had different reactions from friends.
My DS has multiple food allergies. The Nursery refuse to have him in when they have the manager/ usual chef out as they consider it too big a risk. They for example are both out today so can't put him in today when I wanted to work an extra day this week. I won't be able to add an extra day either per week as on one day chef is often out and they get supply chefs in, so limited to working 3 days per week. I consider it a little nervous but think they know the place well and if they judge it unsafe for him then it's probably best he's not there. My friend on the other hand claims they are not being 'inclusive' as they should, by limiting him to certain days/ not allowing all extra days as many parents use.