The transformer will have some markings on it, I think....for example 240v, AC, 12v DC 2A...things like that. So - 240v is volts in, AC is alternating current (which is all UK mains). 12V = 12 volts out, Direct Current, 2Amps...that is the output of the transformer. If you can find these markings it should be simple enough to find a transformer to suit.
John, October 2009