Not on the mortgage, and not on the booking deposit. The return is filed after closing and the money is paid then.
A genuine, reasonable price for furniture is not part of the price of the house. Inflating it is not an option.
Stamp duty on a new house is charged on the price before VAT, so the figure is lower than the headline price suggests.
Buying a site and building on it is treated on its own terms. Ask us before you sign anything on a site.