We also found that our double glazing is a bit draughty in places so my husband has attached these draft excluding sponge pieces down the problem areas, also down the back door. This was inexpensive to do.
I would like some new windows at some point but this is a project for the future. I feel that making sure your home is as efficient as possible is the key to not wasting too much on heating. You can then add other elements like blankets, sweaters and hot water bottles where necessary. I agree with frugal queen on keeping up with the hot drinks, have you never noticed how sometimes if you drink a cup of tea quickly you go really hot? Instant central heating.
I think hot water bottles are great and its amazing how much warmth can be obtained from something so simple. You can get loads of cute ones with covers on now, which also keeps them warm for longer.
I saw this one ..