If extending the ring is really inconvenient, then it is OK to spur off it, especially as these spurs are fused down for dedicated appliances and will not be used to supply sockets (which is less preferable).
What is the rating of the protective device for this circuit, and what size cable is used?
That socket on the far left is only shown as having one cable. If so then this either a radial circuit, or a spur off a ring. Does your washing machine(?) single socket have 2 cables running through it, indicating it may be on the ring?
Maybe you can intercept the cable between the right-hand socket and the JB and place the FCU on the ring(?), or maybe sod's law dictates not.
From your diagram, the best place would be that socket on the right. Keep the unfused part of the spur (before the FCU) short. I think 3m is the limit, but the shorter the better.
There is nothing inherently dangerous about having two spurs from a single JB, but the terminal capacity must be capable of securely accomodating all the conductors and rated accordingly, and dressing 4 x 2.5mm² cables (I assume) in the JB may be tricky. I would avoid this if you can. If you can avoid JB's entirely, that is good.
I do recommend you determine which of those existing sockets are forming the ring (if it is a ring) before spuring off any of them. If you get this wrong you risk a non-compliant installation. An LABC inspector would be asking all these questions.
