The challenge of this assignment is to tease out the resources that specifically look at British national identity vis-a-vis England, Ireland, Wales, and Scotland. Keyword searches are unlikely to be very helpful in this regard. Instead, you may wish to make use of Library of Congress subject headings. Here are some examples:
Don't limit yourself to just what's available in Collins Library; request books from SUMMIT, too! You'll get the book delivered in about three to five business days.