The decision to charge a security deposit to guests is up to you.
ShareCover does not require that policyholders have a security deposit on their property listing. And having a security deposit on your property listing does not affect how you claim with ShareCover.
Many recognised sharing economy platforms like Airbnb, Stayz, or TripAdvisor offer hosts the ability to charge a security deposit as part of their listing. Moreover, Airbnb, as one example, provides guidance on how to add a security deposit to a listing and how Airbnb handles security deposits, among other security deposit related issues. Similarly, Stayz provides information on how to setup a default refundable damage deposit for online bookings, and how to claim this deposit.