Dealing with the Police
If the police arrive, don't open the door, speak to them through the letter box. Explain that you are not a burglar; you are living there because you have nowhere else to live. Do not say that you broke in. You can say you were walking past and the door was open.
Be polite but firm with them. Once you are inside a place and have "secure access", (i.e. your own lock on the door) the main danger of arrest and prosecution is over. Try to get the front door reasonably secure as fast as possible (i.e. change the lock).
If the police insist on coming in, tell them that no arrestable offence is taking place and they should leave you alone. In the unlikely event that you are arrested, phone RELEASE (020 7603 8654) and they will put you in touch with a solicitor. You have the right to make one phone call. The police must release you within 24 hours, or charge you. You still do not have to tell them anything other than your name, address and date of birth.