Just about to do the final connections at the CU end for my kitchen/
diner refit.

Conundrum: I originally wired this as two rings, one for the left
hand side, one for the right hand side, as there was a pretty heavy
appliance load one side in particular which even with diversity took
up too much of the 32A to leave enough for it to be a single ring.
That was going on the online instructions for the appliances in
question. Then I checked on the telephone, and was told that one of
the built-in ovens needed a 16A supply. So things got shunted around
and the heavy appliance load ended up on a 40A radial to a mini-CU
feeding the ovens via radials.

Anyway, this leaves me with two rings, now massively over-specified.
Which I want to reduce to one ring for that floor of the house, no
point in wasting the CU way, and having a more complicated and less
obvious layout than it now needs to be.

The two rings run different routes back to the CU, when they leave the
dining room they go all the way through a 30ft cellar to the CU. I
can easily intercept them near where they enter the cellar, and
interconnect them so they form a single ring. But that actually makes
the circuit path much longer and is more work than just connecting
them both to the same MCB as a kind of doubled-up ring. The latter
instinctively feels wrong to me, but I can't put my finger on what
would be wrong with it, so I am wondering if I am making work for
myself.

(This is all subject to a building notice and inspection so part p
comments are otiose.)