Correct me if I'm wrong but I believe ducks and geese can be outside, just not with access to water that wild birds use. Unless I hear otherwise that's what I'm doing with mine anyway. I currently have surplus ganders in my flock and if confined they will fight big time. The youngsters need to go in the freezer but currently there's no room due to having recently filled them up with our lamb and pork!
I think they still have to be in a netted enclosure. Extract below:
Biosecurity and preventing welfare impacts in poultry and captive birds
Advice for all captive bird and poultry keepers (including game birds, waterfowl, and pet birds)
03 November 2021
Domestic ducks and geese
If housing is a government requirement and you keep small numbers of ducks and geese, it may be possible to house them. If this measure is not possible, ducks and geese should be kept in fully netted areas or temporary netted structures, where practical. All feeding and watering should take place under cover. You should consider using wild bird deterrents to prevent contact with wild birds. Where possible, avoid keeping ducks and geese with other poultry species as they often don’t show any signs of disease but can still pass it on to chickens, turkeys or other poultry species. End.