Hi BML
I would suggest looking into hikvision turbo HD as its a far more cost effective system for domestic use than a full IP system , plus it doesn't need masses of configuring unlike an IP system does & a mild knowledge of networking is involved. The hik analogue HD systems are literally plug & play , you can even install POC (POWER OVER COAX) cameras , where its literally an rg59 cable from your DVR direct to each camera , otherwise you would use shotgun cable (Rg59 + 2 core power ) or even aa cat5 to each camera then install baluns on the end of the cables , the hik 5mp HDTVI cameras arnt to expensive either , neither are recoders , 5mp camera about £40 & 4 way DVR is about £90 , add some storage too it , a power supply for camera & a bit of cable ..... also there's the added bonus of video & audio being recorded. In my personal view of domestic CCTV analogue HD is half the price of an IP system.
Hope this helps