Holy crap that EPC. Let me break it down for you. EPCs are vastly inaccurate. We lived in a stone cottage with single glazing and it was an EPC E41, so, better than yours.
The reality - because it was also detached and very exposed was that we got through the entire year's worth of KwH on the EPC within 4 months in heating alone. The people who assess these also don't seem to account for area: you could be at the top of a mountain in Scotland and they won't calculate the energy efficiency any differently than a suburban road in the middle of London where you get a ton of residual warmth coming up the ground from neighbour's heating systems.
I've done the sums on your EPC on the basis that yours is inaccurate as our last, detached stone house:
The kwh stated x 160% = 122,876 kwh per year (before you even turn on a kettle) - bear in mind we're both at home all day so we use more (which accounts for an approximate 40% increase in kwh in terms of how many occupied hours they assess on)
There are 10.36 kwh to each litre of oil, so your oil usage is 11,860 litres per year.
The average cost I pay for oil throughout the year (lowest since 2023 56p, highest 86p) is around 70p per litre.
At that cost, you'll be spending £8,302 per year on heating oil.
BUT.
When we first moved into a house that was on oil (summer 2021), oil was 45p a litre. Locals were reminiscing about the summer three or four years ago when it was 26p a litre - they thought that summer's price was a rip off. This is where the view that oil is cheaper than gas seems to have come from. It used to be, but at this very precise moment in time, it's pretty much neck and neck.
Come March 2022 when the Russian invasion of Ukraine had been going on for a month or two and oil supplies from the region were cut off (or lowered? I forget), the price of oil rose to £1.30 per litre.
OIL IS NOT REGULATED. THERE ARE NO PRICE CONTROLS. THE GOVERNMENT WILL NOT STEP IN AND SAY 'COUNTRYSIDE FOLK ARE GETTING RIPPED OFF, WE'RE GOING TO CAP YOUR PRICES, YOU NAUGHTY, NAUGHTY OIL BARONS.'*
Guess what happens during a crisis like this? The members of OPEC get together and decide they're going to release 1 million fewer barrels because they want to keep their prices high. This happens often depending on market conditions throughout the world (my weekly oil price email has a handy world update).
I doubt very much that we're likely to see an oil crisis as bad as 2022 as the world seems to have woken up to energy security, but, let's take a doom-mongering view:
11,860 litres of oil @ £1.30 per litre = £15,418 per annum
Now, if that Aga is one of those old electric ones like ours whereby the only way to use it is to keep it on all day long (yours is slightly smaller), you currently need to add:
£6240 per year to keep the Aga on 24/6
That brings your energy bill to over 22k per annum before you've even put a washing load or dishwasher on.
I'd like to re-state this is an extremely doom-mongering view of the world (we literally had to move house after that invasion - it took AGES for oil to even get back down to 90p) - but, do ask yourself, if the very worst happens, is that house 22k per year on energy level of 'lovely, my absolute dream home' - or is it not?
The other thing is the potential to upgrade. Yeah, you can make your energy cheaper by making the suggested changes but a top rating of E46 still means you're going to be absolutely balls off cold all year round.
I had a flip through the photos and LOL'd at the itsy bitsy wood burners and the teeny weeny miniscule heaters in the room - does someone from the Antarctic live in that house?
You're all gonna be huddled round the floor underneath that Aga, OP. Cos nowhere else in that house is going to be warm in winter, imo.
Ofc, it's possible they've shoved up insulating boards and/or insulating thermal lining wallpaper which might help - neither of which will hit the EPC. But, vaulted ceilings + wooden walls = you need MANY, MANY very vast wood burners in that house.
Sorry for the essay. Wouldn't bother if you weren't a complete countryside newb.
*the government gave people with no gas supply an additional £200 towards energy bills in 2023 (on top of the £400 electricity credit everyone got), which they paid directly to the electricity company, in bloody MAY, haha