I wish I knew a way to keep them out Amanda.
We are surrounded by badgers here and I just don’t dare to grow strawberries and sweetcorn. Not only for fear of losing those crops but for worry of the other damage you describe. At least here they do not go for my carrots, I just find a large hole every so often.
Even if your allotments’ site was fenced, there is always the gate, sooner or later it will be left open.
I would just avoid the sweet veg for now.
