Maybe it's not a ring - had you thought about that?OH, and the MCB that feeds the socket is rated at 20A, which I feel ought to be 32A if it has a ring main in the house.
If it's not then there was absolutely nothing wrong with a branch running to the shed.
You were making design decisions without even finding out the type of circuit you were going to use to supply the shed?
And how would you test that?If there is a spare space fora new MCB, would rather run new radial dedicated for the shed,
Come to that, how will you test any of the work you plan to do? Do you know what tests to do - what sequence to do them in and at what point you would energise the circuit(s), and for each test do you know what is being measured, why it is important, how you would carry out the test, and with what equipment, and what sort of results you would expect to get if everything was OK?
That was answered 10 minutes after your original post.but still need to know whether to terminate the earth at the outside of building and use rod for shed, or continue house earth to the shed?
Not only are you woefully underestimating the amount of things you need to learn you can't even be bothered to read the answer to the 1 single question you thought was all you needed.