I'm having trouble visualizing how a US-spec electrical plug could possibly be forced into a UK-spec socket.

Having said that you did the right thing to pay off the hotel and maintain your relationship with the management. It's clearly not the hotel's fault. If you had deliberately taken a fire ax to the credenza the assignment of responsibility would be the same. While obviously the hotel has liability insurance, if it did not hold guests responsible for damage they cause, there would obviously be a whole lot more damage going on with all us living out our Keith Moon fantasies.

Homeowner policies vary wildly on stuff like this (though I would hazard that a "standard" policy would not reach this far); just have documentation for your agent. Did you take photos?