This option is available even if the problems don't seriously affect health and safety or the physical condition of the property. They shouldn't be very minor issues, though, because those probably wouldn't justify filing a legal action.
As always, the best place to start is by notifying your landlord in writing of the repairs that are needed and giving them a reasonable time to fix them. How long is reasonable will depend on how serious the problems are. A good rule of thumb for most problems is at least 14 days unless the problem is very serious or fairly minor.