Translating short words like in, at, or to can be tricky because there's no general rule for this in Italian. But here's something to make your life easier: usually you can use the word in before the name of a room.
When talking about a specific room, you can also use in combined with il, la, etc.
The word table is very special in Italian. When you're talking about a table as just a piece of furniture, you use the masculine noun tavolo.
But things change if you are talking about a table that is set up for eating or if someone is eating at a table! In these cases, you'd use the feminine word tavola.