Where I lived, in the deepest, darkest regions of Bavaria, on the Austrian border, it was the
Krampus who came on the 5th of December to scare the crap out of kids. An altogether more alarming figure than even Knecht Ruprecht, the Krampus always disturbed me. I do wonder about the psychological damage to kids who grew up with that Alpine tradition.
To address the original question, no, St. Nicholas is largely unknown in the UK, although most will be aware of the link to Santa Claus. The Eve of St. Nicholas is not celebrated, which is undoubtedly partly to do with the Protestant/Puritan tradition of the UK.
More generally, Christmas is far less of a religious festival in the UK than in Germany. Despite the carols and the nativity plays and the fact that midnight mass is the one time of the year that many go to church at all, the actual Christmas celebration is largely a secular, hedonistic celebration of consumerism (always celebrated on the 25th, rather than on the evening of the 24th).
It is one of the curses of being a translator that I often have to translate Christmas greetings. They simply do not translate from one culture to another. It is impossible to translate the word "besinnlich". We simply do not wish people a "contemplative Christmas". Christmas is a boisterous and often testing time in the UK, not an opportunity to reflect on the past year in the bosom of one's family.
