>>> it's not as if you can go to a box office and buy them
Er, do you mean like the one Exhibition Way, which is open from 0900 to 1800, Monday to Saturday?
Or, of course, you could phone the Scottish Exhibition & Conference Centre's booking facility (which handles ticketing for the SSS Hydro) during the same hours (and also between 1100 and 1800 on Sundays).
From the SSE Hydro's own website:
"Advice from the National Arenas Association (NAA): Always call the venue Box Office first" !!!
http://www.thessehydro.com/book-tickets/faq.aspx