It's a hard question to answer for me as we don't have much that's uniquely British.
But I like our art, in all its forms, and all our different kinds of scenery. And what welfare state and healthcare provision we have left at this point.
I think culturally we do have some very fine principles, it's just that most people are terrible at accurately translating intention into action. And at accepting resposibility, learning, and doing better in future, when they fail to do so. And while intention isn't entirely irrelevant or worthless, action is the far more important thing.
So I'm glad we have these ideas about fairness and justice and tolerance, because it's better than not valuing things like that at all, even in theory. But I am thoroughly disappointed in the general lack of interest in actually putting them into practice.
I think our understanding of ethics - including of the relative importance of action vs intent - is improving, albeit all too slowly. But that's a global thing, driven strongly by the knowledge, research abilities, and contact with people outside our immediate sphere, that the internet has brought us.