Thank you for your detailed reply which makes perfect sense and reinforces my understanding. Some previous posts on here gave the impression that with each change of government , or indeed after each general election, the slate was wiped clean and we started from square one again.For a government to change previous law, it has to go through the full process , if it is in the manifesto the Lords cannot totally block it.
As I understand all Wuropean Law has to be incorporated into UK law by parliament and can be reversed, by the same process. Of course some of these laws were passed as they were agreed by treaty with Europe and repealing them would put us in defiance of signed treaties.
Not all European law that we have incorporated , is covered by treaty, far from it. Also very frequently we have passed laws which go far beyond what was required , so called gold plating.
I am not sure about the Human Rights legislation , which probably put us in this mess , due to its incompatibility with Common law. We certainly had an opt out, negotiated when we joined as it was one a of the basic requirements.
I cannot see parliament being in any hurry to remove any of the last 40. Years of legislation when we leave though