This protection if needed is often much more expensive if taken through the actual card issuer, if you require it for peace of mind (sorry can't advise on that bit).
You can often find payment protection much cheaper from independent providers. Take a look at the link below, it has a detailed Five page PPI / IPI informative explanation guide with a separate comparison function... that allows you to obtain alternative quotes.
http://www.moneysupermarket.com/payment-protection/