Tanking doesn't have to be very expensive.

I don't think thats true though

Covering the walls in thin polythene dust-sheets will stop the water
evaporating into the room.
I'd personally go with something like making a very simple frame to hold
the dustsheets a couple of inches off the wall, and a fan to blow air
from the room through this space out a vent.
Just covering the walls and doing nothing else may be enough, if it's just
damp, and not water seeping in.

Trouble is that by doing this you are keeping the bricks wet whereas
at the moment they evaporate moisture into the room. Eventually the
bricks will fail and either the house will be knocked down or it will
have to be partly rebuilt - both expensive options

But you might decide that by the time this happens you will be long
gone and meanwhile you can get more house room in which case ignore me

I would just limewash the walls

Anna

~~ Anna Kettle, Suffolk, England
|""""| ~ Lime plaster repairs
/ ^^ \ // Freehand modelling in lime: overmantels, pargeting etc
|____| www.kettlenet.co.uk 01359 230642