Take a look at the information displayed on your charger's plug. It should have a line that starts with "INPUT:" If what's listed next is a wide range of voltage, such as mine which says "100-240V~" you should be able to put a travel adapter on it and plug it in without fear. It used to be that devices made for the US market would burn out if plugged into 220-240V outlets, such as you have in the UK, or we had when I was growing up in West Germany (which I learned at an early age with a fan I plugged in to help something I'd painted to dry), and you needed an electrical transformer, but most consumer electronics today have switching circuits in them to automatically handle a wide variety of voltages.
So, check what yours says, and if it's capable, plug it in and charge 'em up.
Thanks for the quick response!
I have actually realised the battery charger they provide is one of those usb plugs so I can just use the plug for my iPhone charger and it seems to be charging them okay!!
I do have one concern though, which could be unfounded! I am just assuming it has run out of battery, the light started flickering before it eventually went out and the sound stopped, however, I have just removed the bottom to access the batteries and now it has turned on again. The light started flickering again and soon turned off but there is still sound coming out of the speaker? I can't have broken it as all I have done since I received it is just look at in a swing it around a bit. I didn't buy it for duelling I bought it just to look at and have on display and play around with a bit!
Thanks!