I am either confused or this is bull-whotsit. I had a look at Boingo's website and did a quick search on Reading, UK. All but one of the 3 pages of results were so called "Premium Locations", which had an additional per minute fee, and the McDonalds in Reading is no premium location in my book.

The Global tariff didn't mention anything about being exempt from these

So far it looks like a con to me, they should call it the "Itchy and Scratchy dollars" tariff...