I have just moved back to England from China where I bought a HTC Explorer.
It has issues with Google Play, and its market place is a Chinese version so I want to reinstall the OS to an English version.
What is the best way to go about doing this?
You could try changing your system language and then see if play store takes the cue. But if the system language has been coded into the build.prop then it would be of no use as your play store would still show Chinese version and apps specific to China. The only alternative you have is try to flash a European/WWE RUU for your phone. Read up on what RUU is else you could possibly brick your phone.