Well I did a search for British food stores in the Chicago-land area for you, I found a couple that you might pass on to your friend,
British Accents
116 Old McHenry Road
Long Grove, Illinois
Phone: (847) 913-0855
Details: Good selection of British foods, gifts etc.
Winston’s Market
7961 West 159th Street
Tinley Park, Illinois
Phone: (708) 633-7500
Details: Probably the best range of British and Irish food I have yet seen in the Chicago area, everything from “proper” bacon, freshly made Cornish pasties, you name it they pretty much have it.