I can really recommend a small pond or two on your allotment (if the committee rules allow of course!) to attract frogs and toads who do a great job of patrolling the beds against slugs and snails.
Just remember to build in a slope of stones or a shallow bit where other critters such as hedgehogs can get back out if they fall in and place a stout grid over the top to stop children from falling face down into your pond.
The wet cool weather has really brought the slugs out but so have the frogs who like the same conditions.
