There certainly are turnings where the no right turn sign is only illuminated at certain times. The right turn from the South Circular into Hither Green Lane always used to be banned in the peak periods although it doesn't seem to be at the moment. The problem is that it is difficult to enforce this sort of ban.

If there is room, the best way to block right turns into and out of Devonshire Road would be to install a central island. However, the road is pretty narrow there and there might not be room. Having seen what people do to get into Wood Vale, I wouldn't be too surprised to see people doing U turns at the traffic lights to get into Devonshire Road if they were blocked by an island!