Central heating system on 100 year old house. From scratch.how much?

Hi there. Real long shot but I’m looking to buy a beautiful Edwardian period home that’s 100 years old. The catch is that it has no central heating whatsoever.

The house is mid terrace and 120sqm. Windows are double glazed and only two exposed walls. Assuming minimal insulation and I’d be looking at a gas boiler system as gas on the street and I believe that’s the cheapest option.

Rooms in the house are generally 8-18sqm each.

Does anyone have any idea on how much a central heating system would cost. Google it and quotes come up from anywhere from 5-15k

With builders I’m assuming everything will double or be somewhere far beyond the quote.

Anyone have any real experience on this or advice?

Thanks internet 👍