Qualified solicitor are you? I would check said contract, it probably has a cancellation term that states the service can be withdrawn at any time with liability limited to the amount of any monies received to that time. If you have no written contract, then the default liability for the contract is the total value of the contract, which by definition is any monies received until provision of services. He has offered to refund the money you have given him, so he's done everything required under UK law. I wouldn't waste your time chasing this legally as you won't get compensation, just take the refund and spend it on something else. He should only pay for it if you have fully compensated him for provision of services, but again he can refer to the cancellation terms at any point. That aside, it was a bit off for him to expect you to pay the rental for the equipment as he should have a spare.