I have a CCTV Company that supplies and installs CCTV. 
I would recomend you have a look at AData web site and look for 
their special bundle deals, the other one I would recomend is CCTV Direct. 
far superior to Maplins plug and play crap. Get a minimum of 600TVL Cameras 
with Infra Red Night Vision up to at least 30mtrs, get a stand alone DVR with 
Motion Detection and at least 500gb ot 1 terra bit Hard Dive,. 
You can also set it to be viewed remotly on your Iphone or any other smart phone.. 
Good Luck