Ideas how to insulate old house

You could call your power company for a free energy audit where they use the thermal camera to show you where your losing heat. The walls were insulated.

When I moved into my 40s house, I changed all the door weatherstripping. The floor joists were insulated in the crawl space.

I insulated all the electrical plugs.

Where do you live? What and how much did you add to the attic?

That leaves the walls and floor, it looks like. See if you don't find this helpful: http://thecraftsmanblog.com/how-to-insulate-an-old-house/

Don't forget to insulate electrical sockets...it's very, very easy to unscrew the plates and add a foam rubber insert.

...Cavity wall insulation............There are specialist in UK!

Aside from the walls, the next best thing to do is under the house. If you have a crawl space, put down 8 mil plastic and run it up the foundation walls about 2 feet. I believe the new UBC (Universal Building Code) even calls for new construction to have it done. You can also insulate under the floor with rolled insulation attached to the beams. Spray foam is the best, but more expensive.

Sorry, can't help you there. The only thing that comes to mind is that there comes a time when what you are doing becomes not cost effective. Have you run the numbers?

Storm doors. Also they make a foam insulation to pop in behind electrical receptacles.