Do i need a builder or a plumber?

[paranoidmumdroid]

We have patches of bubbling paintwork on a semi-exterior wall (was exterior, now inside a glazed side return).
This corresponds to where copper pipes from the downstairs loo disappear under the floor (see pic). There are also blue rings around the base of the pipes..... so i have a leak somewhere, but my problem is that these pipes are set in some type of cement on the edge of the tiles.
So my question is, can a plumber deal with this? Or do i need a builder?

I am in North West London, where tradesmen prepared to do small jobs are scarce, so I want to be chasing after the right type of guy!

I would think a plumber

To be honest those puppies are probably colder then anything else in the room and are this attracting condensation. It might just be a case of fitting insulation to the pipes (and the usual stuff about ventilation, not drying washing inside etc)