Washing one's *whatever* ass/arse... was a problem for years. Never been in a house with a bidet. But a few years ago I discovered Viva paper towels which can be used after TP by dampening them slightly. They are both soft & strong. I get ones with half-sheet perforations and can fold it over a couple of times. It has made a huge difference in cleansing. (It is not to be flushed! Sewage treatment plants don't like them)I have a small lidded container with a plastic bag beside the toilet which I empty once a week when trash is collected.)

   I have no idea what is available the UK, but it is a great luxury in my old age. Slightly more expensive than toilet paper, but I think I save in the long run by needing far less TP.