Yes, as I recall it had a box wire connector widget, where do I find out what voltage (I assume somewhere on the bottom of the pot or such like, what am I looking for, or will it be self evident),
If it's marked on the pot, it will most likely be either next to the socket or on the base, and be either a label or stamped into the plastic molding. It could be elsewhere on the unit though. You're looking for something which gives any combination of voltage, current, and power, e.g. "12 volts 2 amps" or "6 volts, 24 watts" (or the shortened equivalents, "12V 2A", "6V 24W" etc.
Unfortunately, although the power unit would almost certainly be marked, the pot/tree itself might not be, so you may be out oif luck. The only other way to determine the details (unless you can find the exact same model on sale somewhere) would be to see what bulbs are used.
and what shop will have the replacement part?
A generic replacement could be obtained from many of the consumer electronics stores, or from mail-order places such as
Maplin Electronics. (You're in Belfast at the moment, right? I think Maplin has a retail outlet in the city now.)
Guys in stores live for that kind of thing...right, Paul?
Well they used to! Sad to say that some of the guys in the stores these days have neither the knowledge nor the interest anymore to do anything beyond sell the things they've been trained to sell. Some stores even have a policy of not giving out advice on such things due to the dreaded L-word (liability).
A smaller, family hardware store is more likely to be accommodating in something like this. Unless you can find some geeky type of character in the neighborhood to help you out of course!
