Ideal Standard, Armitage Shanks, Shires, Trent and Caradon which is also Twyfords and Royal Doulton are the usual British stuff plus. They make all kinds. Then you can get reproduction sanitary ware made by the likes of BC Sanitan, Taps Etc, Shaws of Darwin, The Imperial Bathroom Company, Heritage Bathrooms, The Albion Bath Co Ltd, Lefroy-Brooks Ltd, Thomas Crapper and Company Limited. Which is best? No idea. The first couple have been around for years and years and so one assumes they make good stuff. And the products of theirs I have used have always usually been good.
The luxury stuff made by the other companies I am not sure about, having mostly been an employed plumber and just fitted the stuff I did not ask where it was from. Incidentally B and Q stuff can be British made and good quality as well as some difficult and weak stuff they sell.
If I wanted fit and forget stuff then I would probably choose Armitage Shanks but then I am oldish and practicality rules rather than looks. If it is the ladies choice the first group of companies still do a good range of nice stuff, which I am sure the others do as well. It depends what you like.