In reply to ceri:
> Problem with heating is that it warms up quickly but immediately loses heat again. Our central heating works off a thermostat in the main house, so doesn't keep the kitchen warm. There used to be ventilation (a very technical hole in the wall with a metal grid on the inside which made it even colder) but that was lost when kitchen cupboards went in. There is an extractor fan.
Does the kitchen have any heating? You can get fan heaters for under the units.
> At the narrow end of the room (it's not quite rectangular) it is only 86cm from cupboard door to cupboard door, so we can't really afford to lose 16cm
Worktops and cupboards don't have to be standard depth (though machines and ovens do!), they can be modified and some insulation will be a big improvement on none.
The brick boxes at the back of old terraced houses are always cold, there's a lot of uninsulated wall, floor and often uninsulated roof usually plus a draughty door. As a small space a correspondingly small amount of heater often gets put in or none at all.
If the damp is penetrating or roof related rather than 'just' condensation a rebuild gets more appealing but it won't be cheap by comparison with sorting what you have.
jk