So, does your sense of aesthetics rule out using grid-switch FCUs in the
relatively-distant cupboard? That'd take up only one double mounting
box; and with FCUs controlling the spurs to each dedicated socket,
providing closer protection for the cables, the runs from there to each
socket can be in 2.5mmsq.

The "Big Red Switch" does have appeal, but isn't feasible with a ring
(not without bizarre contact arrangements to switch both sides of the
ring *and* preserve continuity of the rest of ring when you bypass the
relevant section). Unless, that is, you have a truly dedicated kitchen
ring, and can replace the twin 2.5mmsqs running back to the CU with a
single 4mmsq or 6mmsq (6mmsq is safe bet, 4mmsq needs calcs on permitted
length), and you put a 45A cooker-style isolator at the point where the
thicker incomer fed out into two arms of the kitchen ring...