Depends on what your justification for it is and how far you are prepared to go.
I remember some of your previous posts and I remember that your STBX has treated you very badly indeed. I cannot remember if you have actually been physically assaulted by your STBX (sorry).
I'm not an expert on the law, so please don't take my word for this and do some checking out yourself, but I think he has every right to force entry into the marital home (assuming it is in both your names) unless you can demonstrate you have good reason to feel that your safety is at risk. You can go to court and get an emergency injunction to keep him away if you need to go that far.
However, even with no legal safeguards in place, if he turns up, finds he's locked out and starts shouting, all you have to do is call the police and they will insist he leaves.