Raymond,
Tell your friend to try Mixx Up Sugar Free Stimulation Drink from Lidl. [/b]29p[/b] (definitely pence!) per can. (or 6 for £1.60'ish)
I drink it every morning (I can't stand coffee!) and I can say that it certainly DOES give me a little boost. Don't go overboard with them, though. If I have more than 1 I find I have trouble getting to sleep at night.