I would change the taps to one with a shower outlet. Is it not a human
right to be able to take a shower?
It's a doddle and a mixer can be picked up very cheaply... Ultra do some
nice ones that are a good price.
At the end if the tenancy she can offer to leave them for the next tenant
or just pit the old one's back. I would charge about £75 for this plus
mixer at say £60 so that's a figure to have in mind.
It's better to beg for forgiveness that ask for permission
YouTube want to silicone the shower rail/bracket to the tiles rather than
plug'n'screw, that way you can remove it all without evidence.

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