Gov.uk is a goldmine for stuff like this. Incase you haven't already had a look here's some stuff that might be of interest.
Wills, Probate and Inheritance
https://www.gov.uk/wills-probate-inheritance/overviewInheritance Tax
https://www.gov.uk/inheritance-taxNot sure if that'll tell you anything you don't already know, but it'll give you an understanding of the legislation behind it at least.