Downstairs toilet or dishwasher, what's more useful?

[trailerpark]

We are in a small house and there is a tiny room downstairs that could be turned into a downstairs loo potentially, or we could move the washing machine in there and get a dishwasher in the space it creates in the kitchen.....
Which do you think would be more useful?....we have two smallish children...

Massive thank you for all your help and advice everyone you are great. I will do as you suggest LL0015 and get some quotes on what's possible...council trading standard site you say. I will take a look.

Advice still welcome.....getting a dishwasher though.