Wait until he goes out. Get a locksmith round. Change the locks. Leave his stuff in binbags on the front doorstep. DON'T, under any circumstances let him back in. Phone the police if he gets arsey or aggressive.
Looks like occupancy rights apply to anyone with a rental agreement or contract. I'm guessing he's trying it on, while assuming you don't know what he's talking about. Trying to post a link [http://www.housingadviceni.org/families-and-sharing/living-together/your-rights-if-you-or-your-partner-own-your-home.html#wipLive-23089-8 here]
Ffs of course the op can't just change the locks when he is out. How horrible and unreasonable is that!
The law is different depending where you live. Presuming you are in England have a look here: http://england.shelter.org.uk/get_advice/downloads_and_tools/relationship_breakdown
In a nutshell yes your partner could get an occupation order to give him some time to find somewhere. He could also attempt to show he has a beneficial interest in the property. What he is not allowed to do is decide he wants to stay living in your home indefinitely if you don't want him there. If he is violent or abusive you can have him removed by the police.
If you have children it gets even more complicated.
I don't think it's that irresponsible or horrible, seeing as there has already clearly been a period during which the OP has asked him to leave and he has refused and stated his intention to make a claim on it.