"Wash up" in UK = US "Do the dishes"; if we wash ourselves, we just 'wash' tout court. A 1950s UK Davy Crockett children's parody, for those old enough to recall that particular nine-days obsession, went "The Yellow Rose of Texas and the Man From Laramie - Went round to Davy Crockett to have a cup of tea. - The tea was so delicious they had another cup - And poor old Davy Crockett had to do the washing-up" [to tune, obviously, of Yellow Rose]. Unconvincing, the nephew, then about 5, that I learnt it from pointed out, because a second cup is generally poured in the same cup as the first so no additional washing-up would have been necessary!

Note, in connection of 'up, that 'it is up to you' [= 'it is your responsibility to do it'] has of late become confused with the more recent, I think of US origin, 'it is down to you' [= 'you are the person who caused it to happen'] ~~ a fine shade of distinction which it is a pity to lose, I think.

~M~