Not much width to have the usual wash basin. Our downstairs toilet is a similar width, with the essential small wash basin on the right, radiator on the left - it makes for tricky manoeuvring. I have always thought how much better it would be with a hinged, folding wash basin - one which empties as you hinge it up, caravan style.
we have a sink in the top of the cistern in our downstairs toilet as there was limited room for a sink. Cold water only, but fine for a secondary loo