Hi bud,we try to cover these things now on first fix on new builds,we have a switched fuse connection unit above the worktop for isolation,it runs down to a single socket outlet below the worktop.
A method i still use a lot is to place the socket outlet in the nearest cupboard to the appliance,drill a 2 inch hole(whoops showing my age there !! 50mm hole

) somewhere near it out of sight and plug the appliance in there.
Trailing leads are ok bud but they are usually laid on the floor,if the washing machine chucks up on the floor then it gets wet.
I have never seen any laws governing this sort of arrangement.
It good practice for isolation.
Regards
Chris