Just to make sure I'm being clear, the two ends of the ring, currently
both ending up in the CU, would instead both go into a 30A junction box.
Then a 6mm cable would leave the juntion box and connect to the CU.

I'd crimp (and solder) two 2.5mm runs. This way, you know the connections
will still be made in twenty years time, when the junction box is under your
new stone/laminate/hardwood T&G floor.

Christian.