Uh, that looks almost steeper than indicated. There are GU's who can do slopes and individual projects, but rarely. An architect will probably be the better choice at first. Timber frame structures sometimes have difficulties with slopes. Really think about what you need and want. Your walk-in closet can only fit about 4 m of wardrobe. Little for the area. The ground floor can also be used better. At the moment it is still a lackluster appendage. And open the house to the outside. A terrace behind the house with a view of the vineyard will certainly always be cooler in the summer than the terrace on the south side. Plan various "rooms" outside. Exactly how they will be can be determined later by the landscaper with you. Surf through the internet. 2 people with that budget can achieve quite a bit. Is it certain that you will stay just the two of you?