At 64 you don't really have a problem - with most insurers it's 65 that age discrimination starts kicking in. And with an annual policy it's the age when you take it out that counts.
No you are not insured by your credit card company. One or two of the gold or platinum ones for which you pay a fee might offer it but it is definitely NOT the general rule.
What a credit card does cover you for is if the company from which you booked your holiday goes bust you can get your money back.
You might also get a bit of accident cover - eg if you buy a plane ticket and it crashes might pay out a bit. Certainly not enough to pay all your medical bills, etc.