Heating a listed building?

Asteconn

Hello,

I live in a top-floor flat, which happens to be sat a listed building (built in 1880).

The windows are all single-glazed sash windows, the walls seem reasonably thick, but I don't think they have any meaningful insulation built into them.

We have a pretty significant loft space, which comes into the flat in three places (one of which is my room). There's no insulation in the roof. I was thinking of getting some quilts off free cycle and using those to insulate the roof space.

We're heated by storage heaters. We've got 5 of them for the 2 bedrooms, living room, hallway and kitchen. I've only just (yesterday) used the one in my room.

Last electric bill we had, over the summer, was £68. That includes some heavy computer usage.

How shall I go about keeping the place warm without spending a fortune? I'm a student and as such I have next to no budget at all. I live with my brother, who's not in full time education.

edit: I've had a read around the forums on using storage heaters already, and have followed advice of leaving the output on 1 and the input somewhere between 3 and 4, depending on the weather.