You should avoid the Charlie Chaplin re-mastered version from the 1940s. You can buy the original 1925 version in the UK. This is the Park Circus DVD version (not Blu-Ray), which can be purchased from Amazon (it also includes the 1942 re-mastered version but ignore that).
The original Chaplin 1925 version can also be imported from the US for about £20.
The US imported version is distributed by Criterion Films which also includes the original and the updated 1940s version.