I've been lucky until now that we haven't had to consider this in previous homes but we have moved into a 1960s house with no insulation and old single glazed windows.
The boiler and water tank system is old too, not too sure how old but when we got it checked over when we moved in, we were advised to get a new one before this winter (not going to be possible).
Anyway, what I wondered, is it better to keep the hot water on all the time? Keep the tank hot? Or is it better to warm it up only when we intend to have a bath (no shower here).
And what about heating?