Lol, it's not too serious. Serious is when she slows down on eating and starts to show signs of pain. We're soaking her feet in warm water with iodine and epsom salt in it and then adding neosporin followed by a bandaid. We do this daily, and since the infection is still early she should recover in a week or two. In London....hmmm. I'm sure you have some farms there right? Farms lead to feed stores and feed stores lead to chicks and ducklings. Ducklings will go for 4$ around here, I'm not sure about London though. Or you could just do what I did, wait till late spring and find a duck nest. Though I saved the eggs from being crushed, I'm sure you can take a couple but leave the rest.