This area seems particularly prone to plagues of small snails (theba pisana) which appear in force with the onset of summer. Their sheer numbers mean that they are nearly impossible to eradicate, but here are some ideas to help keep them off your plants.
They don't like sandy or gritty ground - you can lay coarse or crushed shells around the most susceptible plants and trees.
Make a beer trap - the bottom of a plastic water bottle burried up to its rim in the soil, half full of cruzcampo. They love it! So much, in fact, that they get drunk and drown happy.
Hand picking - get up early and hit infested plants with a stick or shake over a bag or dustbin lid. The snails move and feed early in the morning, and so are not yet glued in position for the day's sunbathing, and fall off much more easily. Repeated attempts give the best results overall.
Preadators - the most efficient snail-munchers are turkeys and ducks. Get one or borrow one or two and they will follow you around the garden, diligently pecking away at all within their reach.
Time - don't worry, the snails fade away normally during August, and by autumn the problem they present is negligible. They lay their eggs and die, and their shells enrich the soil.
Enjoy and I hope you can get rid of them soon
General Wildlife