How do we say "in a week", then?

"In" in English it is quite strange - we speak of time as if it were place, we say "in the house" and "in a week" using the same word. In Hebrew, however, we have a special word!
"In a week" -
בעוד שבוע
(beod shavua)

You may say: "Wait, but there is another word for "in" - תוך! or בתוך... What's the difference, which one is the correct one and, when do we use it and how?

All these - will be answered in the next post!