So I need to move a double socket 4ft to the right as the existing one is about to be behind a semi built in cupboard.

All chased in, horizontal in the safe zones and ready for wires. (Can’t lift the floor)

Now from my understanding the correct thing to do would be to spur off it with 2.5mm and leave the existing socket as is. It will be pretty unaccessible however and not used.

That being the case why can’t you Wago the existing ring and extend the wires blanking off the original socket but leaving a faceplate on to warn of wires? Is it just that if it’s just one socket then a spur is easier.??

In my opinion you could do it either way.
You would need to Wago the spur as the socket won’t be accessible!

All junction boxes and joints should be accessible which I guess they kind of will be so either way will do

What I’d recommend is extending the ring, so 2 new cables to the new socket. Using wagos, placed in a wago box you can then fill over the joint as it’s maintenance free. As long as everything is still in the zones, that is. If it puts anything out the zones, I’d connect up the same way but put a blank over.

I would just spur off it.

Then you could use the socket behind the cupboard to power some of those trendy lights that come on when you open the door.

Like I did when I fitted my kitchen.