If it was so black and white, there would be no need of lawyers would there be! They have been cases when people cohabitating but not on the deeds have managed to claim an interest in the property, so it does happen.
However, these were cases when they were able to evidence that they money they had given had gone towards the mortgage but more importantly, have done so for many years. This is not the case here, hence his chances are almost none. However, it is not just because his name is not on the deeds, that alone doesn't protect you.
His claim about the work doesn't have more chance though, that is if he could prove that it has indeed added to the value, which from what OP says is not the case, although it is what he is arguing for.
Yes, women get shafted, but they don't bother to go to court. No I don't have legal qualifications but I did seek legal advice and did a lot of reading about it before I moved in with my OH in his property and paid half the mortgage. This was on the understanding that we would be married within the next few years. Still as legally advised, I made sure to put on my monthly transfer that it was a payment towards the mortgage. As it is, we did indeed marry, so it didn't matter so much any longer.
There are also many posts on property forums about people asking how to protect their property when their partner move in with them because although indeed, they are more likely to get nothing in separation in court, it is in no way a done deal, with each year paying giving more chance of making a case of having gain an interest in the property.
Clearly, a year won't do it though!