"Whether you keep just a few birds or thousands, from 14 December onwards you will be legally required to keep your birds indoors, or take appropriate steps to keep them separate from wild birds. We have not taken this decision lightly, but it is the best way to protect your birds from this highly infectious disease." www.gov.uk/government/news/avian-influenza-bird-flu-national-prevention-zone-declared
You have 11 days to make your housing secure, so that wild birds (and their droppings) can't come into contact with your domestic birds.
I'm going to put tarpaulins on top of their pen, I think. They have a coop with a run inside the pen, but it seems far too small to keep them in 24/7.