This company have a wide range of systems, but there are many others who sell on he Internet.
CCTV Direct, CCTV Systems, Security Cameras, Surveillance & IP Cameras
ironically modern cameras do like the dark and actually record at higher resolution in the dark (in black and white) than they do in colour during the day. What they do not like is harsh bright light pointing at the cameras - think of the camera like your eye - you don't like to stare directly at a light bulb. Also if you have PIR lights these will cause the cameras an issue but basically the more constant light the better as with the the correct type of lights positioned thoughtfully you can have 24 hr colour recording which is of a high standard.
You need to decide how much you want to spend as ultimately this drives what dvr you buy and which cameras. Fitting is straightforward hardest part will be drilling the holes and hiding the cables.
Hope that helps.