I had a problem with my floor rising in the living room. I could see that it was something to do with water but I wasn`t sure where to start. I figured I should start with a plumber and I was correct. If I were you, I would start with a plumber. As it`s dripping in your boiler cupboard, I would get a Gas Safe plumber to have a look at it. It might not be anything to do with the plumbing but at least that`s a good place to start and then you can work on a process of elimination.