Legal advise on a kayak hire waiver

I am setting up a Kayak and Paddleboard equipment hire company and am looking for advise on a pre-written waiver. This will be signed and completed online before their hire period. I'd like to know if my liability is covered and I have legal protection if any injuries take place. It is Equipment hire and not an activity led by a member of staff and therefore down to the customers own safety on the water. This is a UK company.