Partner won't leave my house

I have left my own home as partner who moved in in March wont leave. Told him to leave by the 22nd. I dont think he will leave and it looks as if he had either lost his job (would of got the sack if they found out he is drinking at work) or he may of just left and wont leave house. I would of changed the locks on the 24th but if he is in the house how can i. I need my home back so what can i do. Please has any one any ideas, knowledge of the law. I am weary and dont know where to start.