Above is a quick plan I have drawn to give the reader an idea of the size of this toilet shower and laundry, on the left is the toilet, the piece missing is the shower (center), and the missing square on the right is the laundry basin. What I have not drawn is the water heater. that is off the floor and merely restricts the door from opening.  But I shall be taking the door off for this installation as it will make it easier for the D.I.Yourselfer, illustrations.

First things first.
(1) Nobody in their right mind would lay a domestic sheet vinyl outside of a shower. Stepping on this type of vinyl with wet feet can cause a severe slipping hazard.

(2) Laying sheet vinyl over ceramic tiles will lead to un-even surface transfering and will become visible after a short time

This vinlyl intstallalion is merely using the ‘SHAPE’ of this area, this vinyl will be removed after this demonstration