If anything happens and the hospital say they need immediate payment, usually written confirmation by fax/email from your insurers will suffice. Make sure that you have your policy number and contact details, as long as they have it in writing, the hospital should proceed with the necessary treatment, they may request an excess normally £35/£50 to be paid direct to the hospital at the time of treatment. keep all your receipts and names/numbers of anyone that you deal with for your claim, when it comes to settling your claim you should not have a problem. (always remember to disclose any pre existing medical conditions to your insurers when taking out your policy or you may not be fully covered)