Definitely don't use "cent" in your searching for hammered coins - the words "cent" and "penny" only mean the same thing in North America. These coins are pennies, not cents.
If searching for "English hammered", you could try that phrase, but many of the hits will be for coins that are probably later in time than your target period, which for English coins is really 1066-1500. You might have better luck searching for the specific names. "Richard the Lionheart" is a famous crusader king of England. "short cross penny" and "long cross penny" are both names of types of pennies that were limited to this time period, too; searching for "cross penny" should let you find both types at once. Coins of Henry II and III and Edward I, II and III tend to be cheapest.
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis