I need to make a flat habitable again. However, the place is due for
demolition in the next couple of years, so I don't want to spend a fortune.
It had GCH, but that is all sludged up, and the boiler is completely shot.
Besides that, it has a combined cold water tank/hot water tank in the airing
cupboard, and this is also shot.

My preferred solution is to use electric fires for heating, and to heat the
water electrically. I would like to run the water direct from the mains, so
as to do away with the cold water tank. It's only got to serve the kitchen
sink and the bathroom. I'm looking for a hot water heating and storage tank
that can run off mains pressure and isn't too expensive. It needs to be big
enough to run a bath. There are only two places to put the tank, one is 20"
x24" and the other is 16.5" x 39" (both internal measurements).

The alternative might be to heat the water as it is needed, but that will
require masses of new wiring and in any case the electricity supply to the
flat may not be adequate to heat a reasonable flow of water.

I guess that I need to check the electricity supply into the flat is
adequate - is it enough just to check the main fuse on the distribution
board?