Linkle, are you looking for a kit type build or an individual designed one ? Is it for you or a child ?
Try these people although might be expensive for a bespoke one. I got my dolls house from here in the 1980's and didn't think they would still be going. I think they may now live in Ormskirk but the shop is still registered in Liverpool. Lovely people, a little family business.
They were beautifully hand crafted, individual dolls houses.
https://www.yell.com/biz/the-dolls-house-shop-liverpool-901246979/