Hi Claire
I've never personally seen this clause in a contract before so I assume the landlord added it in to protect himself...or make sure he made some extra money at the end.
To be honest, this could be considered to be an "abusive clause" in which case a nice little letter from a lawyer may make him think twice about pushing through with it.
It is wrong really. Even on standard contracts you can leave early by giving a month's notice, that's perfectly normal.
You can not pay the rent (that tends to be quite normal too ) and although he is allowed to come round to the property, it is only with your approval. So you can call the police if he comes round unexpected.
It's a shame really, it sounds like you have always paid the rent, which is really what matters, and now at the end he is going to make it difficult for you. I don't know why some people are like this.
Anyway, perhaps send a message to Maria de Castro, she is a lawyer who posts on here. Am sure she will give you some property advice!
Best of luck with it.
Justin