Cost of heating an older house?

[wanderingduckling]

DH and I are currently looking to move out of London. We're trapped in a cladded flat and cannot sell so we're venturing back into the world of renting.

We have an appointment to view an old 4 bed detached house with sash windows which looks lovely. However, we've just had a look at the EPC and seen that it seems poorly insulated. Given we're going from a 1 bed new build we really don't have any idea what the cost of heating such a place would be. I'm sure the letting agent won't be honest, what does mumsnet think? We'd be working from home and it's gas heating. Any guesses?

I live in a large, detached, early Victorian Villa. It's solidly built with original sash windows, cast iron frame conservatory , high ceilings , huge oak doors and all the original oil/gas lamp fittings and servants bells. It an amazing place and we love it. BUT , our winter heating bill is about £250+ a month , probably more this year with everybody, bar me, being at home 24/7. To be fair they were built when your servants would lay and light a fire in every room plus I think people were more hardy and accustomed to the drafts and the chill of winter. I

Hi Piglet John. Its just down to the order the components are listed in on the epc. When lodging an epc the first construction type on those details say Cavity, filled. So the main part of the property will be of that construction. As the 2nd construction listed is solid - that will refer to an 'extension'. If the order was switched around, the opposite would be true.
The first thing listed will be the 'main', the subsequent listing will be extensions - ie anything with a different wall,floor or roof component to the main. And the main is always the building part with the habitable rooms. ie a bathroom or kitchen would never be the 'main' (top wall type listed on the details) I hope that makes sense!

TVM