We're working hard on adding the ability to reduce the deposit ( £750). We don't have this option yet, but it is high up on the priority list and we intend to add it in the coming months.
In the meantime, you can get cover from various insurance providers that will reimburse your deposit in the event of any incidents. We suggest reading this helpful article from The Guardian which lists some providers that allow you to reduce this from as little as £2.99 a day.