Hi, i'd like to install a power shower on the cheap!

Next to my bathroom is a cupboard that was originally intended for an
imersion heater, i've a combi boiler thingy so the imersion is not
needed.

Can i use the electrical wiring from the outlet intended for the
imersion heater to power my shower. It would save any additional
wiring throughout my home. The imersion outlet is seperate on my fuse
box with an 16A fuse.

Cheers.