i'm not sure whether you can get a usb charger, however you can buy a "universal adapter plug" which will plug directly into the wall. i did this, as i had the same problem in France. i found a universal adapter with several different tips and adjustable voltage which works fine.
If you search this forum for "adapter" or "power supply" you'll find plenty of helpful info, including all the specific technical specifications for what you'll need. you should be able to buy an adapter for only a few pounds.
the output you need is :
Output: 12v DC, 1000mA, center positive.
here is some info about the one i bought :
https://www.mobileread.com/forums/sho...8&postcount=10