Mostly ceramic tiles in my experience, or lino in budget e.g. student accommodation. I've rarely seen wood in the UK, presumably because it is prone to water damage. The problem with tiles though is that they do get very cold underfoot, hence the popularity of "bath and pedestal" mat sets. I did have a place with rubber flooring in the bathroom, and that was nice because it was non-slip, easy to clean, and not so cold underfoot. But I don't think I've seen a full fitted carpet in a bathroom since I last saw an avocado bathroom suite.