Struggling to understand the brief... just to clarify, the laundry bit is existing with the door from inside the house and the bathroom bit is the extension?... also can there be a window in the wall where the bath is?

Ok, leaving the laundry as is coz it's existing I'll focus on the bathroom...

- not sure if the opening from the laundry to bathroom is existing too, but if not I would consider moving the doorway 'down' closer to the wall, which would make the space more workable (p.s. a cavity sliding door would work best here)

- I would add a highlight window say 04x21 on the 'left'/bath wall with frosted glazing for privacy and would replicate that highlight window with clear gazing above the door/wall separating the laundry and bathroom

- if this isn't the main bathroom but an additional one for guests, do you really need a bath in there?... I would swap location of the bath & vanity and have a double walk-in shower along the 'top' 2m wall, with a glass shower screen to maintain light and openness... also better for elderly guest than climbing into/over bath hob

- I would put the vanity, a floating one to maintain openness, on the 'left' wall where the bath was, and I would still keep the window to the street at the 'bottom' but maybe centred on the wall could be better

Hope that makes sense, let me know what you think and feasibility

No worries, good luck and Merry Christmas too :)