Man, that's exciting. Imagine finding that 2800-yr-old stuff, in that condition, in your garden. What a time capsule! I really am fascinated with the history of Britain, and not just because it's part of our American heritage (which it is).
In places where it's certain there will be artifacts, like in very old towns, they sometimes put restrictions on your deed. Like, you can only dig two feet down in your back garden. It's similar to the restrictions put on listed houses.