^ If your'e not hideously ugly and even only mildly charismatic, they'll most likely be happy to give you work.
Bartending courses-- I've said it before and I'll say it again til I'm blue in the face-- are about as effective as wiping your butt with the money and flushing it down the toilet.
Get yourself a decent bartending book and you'll be fine.
99% of drinks you'd mix are standard cocktails: martinis, gin and/or vodka tonics, cosmopolitans, lemon drops, manhattans, etc. Really easy stuff once you get the hang of it. In Ireland it's quite possible that beer is going to be more what you're pouring anyway.