Here are the words with "un-" in front of them:

- dress -> undress
- wrap -> unwrap
- tie -> untie
- lock -> unlock
- do -> undo
- pack -> unpack

Now, let's put each word in its correct space:

I like going away for a holiday but the best part is coming home again. I arrive home. I (1) **unlock** the door of my flat. I put my suitcase on the floor and start to (2) **unpack** it. I take out the things I have bought on holiday. I (3) **untie** the string. I carefully (4) **unwrap** them, look at them and put them on the table. I feel tired but very happy. I go into the bedroom. I (5) **undress** my jacket and shoes. I take them off.