Hi Anton and Welcome to the forum, you might want to have a look at the following FAQ which explain where everything is
Welcome to Benefits and Work DWP will be establishing your basic qualification for PIP. This will include establishing that you have not lived outside of the UK recently. I'm afraid I can't explain the holiday question!
You might wish to bookmark/favourite this on your web browser now so that you can find it easily in future. This will allow you to return with further questions or comments about your PIP without having to start a new topic each time. It helps us enormously when everything relating to the same claim is kept in one place - and I hope you will find it useful too