#1 Loft Insulation, £50-99-199. Get the loft insulated to 300mm or so immediately. You lose probably 35% of your heat through the roof in a bungalow and E7 heaters work by heating the room in a morning then keeping it warm thereafter. Without proper insulation E7 is both expensive to run and goes cold too early.
#2 Wall Insulation, £50-99-199. Get the cavity wall insulated similarly. You lose probably 30% of your heat through the walls in a bungalow, so the same applies, plus the cold surface will create draughts which will make it feel colder. If you do not have a cavity wall the best thing to do is insulation the inner walls of the main living room (where you spend the most time), you can buy 25mm & 50mm Celotex online, then screw plasterboard to the top, simple plaster skim and even Super Fresco Bobble wallpaper looks ok in Barley White Matt (not like most super fresco wallpapers which look a bit hideous, it is small textured and lends itself well to painting).
#3 Floor Insulation, DIY. A floor is about 15-20% heat loss. If your floor is solid concrete the best insulation is felt (3.4 Tog), polyurethane foam (2.7 Tog), Tredaire (1.7 Tog), Rubber Crumb (1.1 Tog), Sod All (0 Tog :-) What is the difference? Well a solid concrete floor with quarry tile & 20yr old green tredaire heavily compacted used to make the lower legs ache painfully if stood on for very long, changing to polyurehane and felt (I know too high) removed that ache and actually made the room warm /in the 2009 winter/. Very surprising. If your floor is wood, you need to reduce any gaps re direct heat loss, then insulate between the joists under the floor. This is done by fixing string or netting to the joists, then pushing down *tightly fitted* PIR foam or cavity bat foam. It must be tightly fitting re no air gaps otherwise the insulation is bypassed. It MUST retain an airflow path under the floor to prevent rot - in that respect you need to ensure the underfloor area is dry or at least ventilated by cross- vents under the floor in the direction of the joists and that the vents are not blocked. This can save you a lot of money re remedial work in the long run.
#4 Draught excluder, £20. Letterbox, windows & doors. You want EPDM rubber type in white or brown, not the foam stuff. P type is for large gaps, E type is for small gaps. if you have modern DG obviously this does not apply.
#5 Reduce ventilation in winter a little. If your bungalow has 1-2 open fireplaces with no gas / real fire in them, plug up the chimney except for a small ventilation gap over the winter. Likewise restrict general house vents - it depends on the age of the house. Do not clog up trickle vents. You want to reduce the house Air Changes Per Hour if they are high (such as a 1950s 12-vent 2-chimney bungalow), but not so much that you suffer condensation and mould (which will not help your health). Generally to avoid condensation you a) remove steam generated in kitchen by extractor fans b) increase heating c) increase ventilation. Unless the bungalow is very old this is not likely to be a problem.
#6 Fit an extractor hood in the kitchen. A cheap one off Ebay "shipping scratched" can be as little as £20. More expensive is getting a hole through a wall, but that is what husbands are for. Same goes for any shower. Just ensure someone knows how to wire it correctly, there are Electrician's Guides out there on Amazon UK website quite cheaply and easy to follow.
Now, Paying for it - Money saving tips.
Food & Domestic. Look at what you buy in a year. You may find certain branded stuff is cheaper at say Asda than Sainsbury's (check the websites). Then buy in bulk when things are on special offer. For example if you buy 52 boxes of Special K in a year that is nearly £150 when not on offer, but only £100 when on offer - £50/yr saved. Eating 2 cheap meals a week can help too, saving £150-350/yr. Put another way, it is easy to knock £200/yr off the total bill.
Electricity prices. Shop around regularly re uSwitch websites etc - but watch for early- switch penalties.
Careful use of energy. If you are on E7, ensure any tumble dryer is on E7 - the saving is £30-75/yr. Energy saving bulbs throughout - they do save about £25-30/yr.
All the savings add up. Saving £200/yr on domestic is the same as saving £200/yr on electricity.
With economy 7 heating insulation is everything. Loft Insulation + Wall Insulation + PU Carpet Underlay Insulation.
Also remember females prefer to be warm - because they get cold easily, whereas males prefer to be cooler - they do not feel the cold much. That can mean a "duvet fight" re one wanting 15 Tog and one wanting 3.5 Tog. So there is a biological difference to consider.
If you collect a newspaper rather than delivered it saves about £100/ yr (if not more). Quite substantial. Same goes with getting all the shopping done on one day vs multiple trips. Same goes with making a list of things you want, then only buying them a month later if you really need them; that way you can also combine online orders to reduce postage charges.
Savings of £250/yr are quite possible with electric heating if poorly insulated. That together with other energy saving measures (£50/yr) and "domestic savings" (£150/yr) can save £450/yr.
You think I am not already doing all of that?
You sound like my husband.