I wonder if "credit references" could simply be having credit information like bank & credit account numbers, utility bills, etc. Having recent copies of statements and bills could be handy. In the US you can access your credit report, and can authorize others (e.g. potential landlords) to access it as well. Is there something like that in the UK?

I'd think that if you can't get copies of your medical records (which people in the US should), write down as much info as you can on your vaccinations, major illnesses and injuries, medicine use, allergies, previous physicians, etc. It would probably be good to keep (and update!) that kind of info anyway - an easy reference sheet. I know that (US) doctors ask for a lot of this info from new patients, and health insurers do too.