You do not need to be fluent. You need about thirty words and the willingness to use them badly. The difference between a traveller who has them and one who does not is the difference between watching a place and being let into it.
Start with the courtesies: hello, please, thank you, goodbye, sorry, and the words for yes and no. Add the market words next, the numbers to ten, and how to ask how much. Then a few that show you are trying, like lovely, delicious, and the name of the thing you are buying. People warm to the effort far more than to the grammar.
Learn them out loud, not on paper. Ten minutes a day on a phone app for a few weeks before you go is plenty, and the saying is what sticks, not the reading. Write your handful of phrases on a card for the first few days, until they come without thinking.
The reward is out of all proportion to the effort. A greeting in the local language at the bakery, the pharmacy, or a neighbour's gate changes how you are treated for the whole stay. You will still get most of it wrong, and nobody minds. The trying is the point, and it is half of what makes a home swap feel like belonging rather than visiting.