Meliss,
CCtv cameras can be simple to install though this depends on how complex the system is, the camera has a power system and also an arial output and input.
In short a few wires, this can be connected either to a dedicated monitor or channeled through you TV, and viewed on your AV channel. more than one camera and you are looking at a switch box unit to convert the signal and switch between cameras.
If its a box standard system it should not take long to setup though as I dont reside in England I'm not upto date on a price to be installed, it should be simple and straight forwd though dont let someone tell you otherwise unless you have a muliti camera unit that you are applying to an office block.
H20