Move the garage to the neighbor's and position the house nicely in the sun. You can reduce the noise with fences and hedges. You will hear the cars anyway, no matter how you position the house. But I can promise you that after a year you won't notice it anymore. We have a railway line behind the garden. I don't even notice the S-Bahn anymore, and they are definitely louder than a car.
Regarding the office: we also don't have a separate room for it. We just placed a wall so that we can put the desk behind it. So it's basically between the living room and the kitchen. That's completely sufficient. I would also forego a walk-in closet and rather integrate it with shelving systems and partitions in the bedroom. Saves space that you desperately need for other things.
Because what you constantly overlook is the lack of storage space. Where are you going to put all your stuff? The attic takes up a lot, but a lot is needed downstairs for weekly use.
Then your budget for the house is really tight. Quite a bit will have to be done by yourself. Because the ancillary costs can be hefty. Just construction power, connection costs for water, electricity, and internet. The sewage pump. The pipework for rainwater and sewage. These are always small puzzle amounts, but in total, suddenly 50k is gone.