I found a cookie recipe which requires "English Toffee bars". I have never seen them around here, and don't know what they are.   What are these bars? Is there any substitution I can use? How close are Toffifee candies?   If it just said "toffee", I would cook it at home. But I am unsure what the differences are between an English toffee bar and normal toffee. Can I still cook it? How does it differ from normal toffee? Or can I just put normal toffee in the cookies?  
English toffee is very chewy - the kind of stuff that glues your teeth together! Once it has been cooked and set, it's not easy to handle and wouldn't be easy to chop up for a cookie recipe. You'd possibly be better off with some kind of fudge which is easier to handle but will still hold its shape in a cookie. 