I am very sorry to hear about Joseph's situation. Short of breaking his neck as a hunter would with a caught wild rabbit, there is no safe or humane way to realistically put an animal to sleep at home. As I am sure you can understand, any drug or chemical that could cause death (like pentibarbitone used by vets to do so) is under strict legal control. This is because what could cause death for a rabbit, could similarly harm a person. So, there is nothing that one can reliably use at home in this situation. And if you were to try a cocktail of drugs, you would risk causing him unnecessary suffering (which I am sure is not your intentions with Joseph).Furthermore, despite it being Sunday, you should be able to reach a vet. Many veterinary practices in our country have office hours today. As well, all of our veterinary practices here do have a legal responsibility to provide contingency plans for emergency care for their patients even when they are not open. Therefore, it is worth ringing the practice. If they are open, you can get him seen now. If they aren't, then they will likely have a message to direct you on how to contact their out of hours service. And if you don't have a vet, you can find one local to you by checking the RCVS Register (HERE) or check the Vets Now website (LINK) to find this chain ER clinic who are open all nights/weekends.In any case, while it may take a phone call or two to reach a local out of hours service, you will be able to have a vet see Joseph immediately. All vet practices have a legal obligation to provide out of hours care and to not leave an animal like this suffering. So, you do need to check the registers if your vet isn't available to find another but there is no reason that your vets cannot see Joseph now to end his suffering and protect you from causing him more harm when trying to do right by him.Please take care,Dr. B.