I've recently moved into a house without a shower. The hot water
pressure out of the bath top is too low to effectively use one of those
hand-hold shower heads that attaches to the tap. I will probably discuss
with the landlord at some point the possibility of getting a shower
fitted, but this may be impractical given the layout of the bathroom -
low sloping roof at one end of the bath and a Victorian sash window at
the other. I was wondering whether there are any practical options for
increasing the water pressure of the tap so a hand held shower becomes
practical.

The pressure is low because the hot water tank is on the same level as
the bath, would there be any practical options to fit a secondary hot
water header tank above the current one for example?

TIA

[crossposted to cam.misc and uk.d-i-y, followups to uk.d-i-y]