I believe it is acceptable, provided it is possible to reach the dishwasher socket itself to unplug it.
A means of isolation for maintenance is required for the appliance. An unswitched socket is OK for this, provided you can reach the socket to unplug it, of course. Obviously, you lose the ability to switch the appliance easily. However, check that the cable to the socket is at least
2.5mm. Otherwise, you'll need to do some calculations to prove it is safe to remove the FCU, as you will no longer have a 13A fuse protecting the cable.Christian.