Are you sure it's £10 in Norn Iron?
The reason I ask is that I had cause to bring the older not so young lad to a GPs clinic on the mainland a good few years ago and they didn't seem to have any system for taking cash. In fact, they were quite put out by the whole thing when I approached the reception desk to settle the bill and, after some discussion, decided his E111 card would suffice. Then we went next door to the pharmacy and were handed drugs in exchange for his prescription, again free of charge.