What should I do about this roof leak?
Being at the wrong end of multiple countries divided by a common language, in the USA I'd be looking for a company listed under "roofing" or "roofers" and preferably one that specifically mentioned metal roofing as something they do. The same people that install them in the first place generally know how to fix them as well. 

As a self-described non-handy person, don't try to go up and have a look. If you can look at the suspect area of roof from the ground (perhaps with binoculars, or a long lens on a camera, and then you could post that image here) you might or might not be able to spot something, but in general unless there's something missing (such as a section of the peak flashing) your roofer will go have a look closer to detect the problem area.

The leak outside is often not where the leak inside is - it's usually somewhat (or quite along way) further up the slope of the roof.

AFTER the leaky roof is fixed you (if you care to tackle an easy start to "handy") or a drywall/plaster repair person would need to fix the ceilings, and then they will need to be painted. Often you can find one company that does both painting and plastering, but some specialize.

Be sure the roof leak is truly fixed, first.